16. Why were the Jews singled out for extermination?
Answer: The explanation of the Nazis' implacable hatred of the Jew rests on their distorted world view which saw history as a racial struggle. They considered the Jews a race whose goal was world domination and who, therefore, were an obstruction to Aryan dominance. They believed that all of history was a fight between races which should culminate in the triumph of the superior Aryan race. Therefore, they considered it their duty to eliminate the Jews, whom they regarded as a threat. Moreover, in their eyes, the Jews' racial origin made them habitual criminals who could never be rehabilitated and were, therefore, hopelessly corrupt and inferior.

There is no doubt that other factors contributed toward Nazi hatred of the Jews and their distorted image of the Jewish people. These included the centuries-old tradition of Christian antisemitism which propagated a negative stereotype of the Jew as a Christ-killer, agent of the devil, and practitioner of witchcraft. Also significant was the political antisemitism of the latter half of the nineteenth and early part of the twentieth centuries, which singled out the Jew as a threat to the established order of society. These combined to point to the Jew as a target for persecution and ultimate destruction by the Nazis.

http://motlc.wiesenthal.com/site/pp.asp?c=gvKVLcMVIuG&b=394663

January 30, 1933 Hitler becomes Chancellor
April 1, 1933: A boycott of Jewish shops and businesses by the Nazis.
April 7, 1933: The law for the Re-establishment of the Civil Service expelled all non-Aryans (defined on April 11, 1933 as anyone with a Jewish parent or grandparent) from the civil service. Initially, exceptions were made for those working since August 1914; German veterans of World War I; and, those who had lost a father or son fighting for Germany or her allies in World War I.

April 7, 1933: The law regarding admission to the legal profession prohibited the admission of lawyers of non-Aryan descent to the Bar. It also denied non-Aryan members of the Bar the right to practice law. (Exceptions were made in the cases noted above in the law regarding the civil service.) Similar laws were passed regarding Jewish law assessors, jurors, and commercial judges.

April 22, 1933: The decree regarding physicians' services with the national health plan denied reimbursement of expenses to those patients who consulted non-Aryan doctors. Jewish doctors who were war veterans or had suffered from the war were excluded.

April 25, 1933: The law against the overcrowding of German schools restricted Jewish enrollment in German high schools to 1.5% of the student body. In communities where they constituted more than 5% of the population, Jews were allowed to constitute up to 5% of the student body. Initially, exceptions were made in the case of children of Jewish war veterans, who were not considered part of the quota. In the framework of this law, a Jewish student was a child with two non-Aryan parents.

http://motlc.wiesenthal.com/site/pp.asp?c=gvKVLcMVIuG&b=394663#top

Historians have documented evidence that as Germany's defeat became imminent and the Nazi leaders realized they would most likely be captured and brought to trial, great effort was made to destroy all evidence of mass extermination. Heinrich Himmler instructed his camp commandants to destroy records, crematoria, and other signs of mass extermination.[16] As one of many examples, the bodies of the 25,000 mostly Latvian Jews whom Friedrich Jeckeln and the soldiers under his command had shot at Rumbula (near Riga) in late 1941 were dug up and burned in 1943.[17] Similar operations were undertaken at Belzec, Treblinka and other death camps.[16]

In the infamous Posen speeches of October 1943 such as the one on October 4, Himmler explicitly referred to the extermination of the Jews of Europe and further stated that the genocide must be permanently kept secret:

I also want to refer here very frankly to a very difficult matter. We can now very openly talk about this among ourselves, and yet we will never discuss this publicly. Just as we did not hesitate on June 30, 1934, to perform our duty as ordered and put comrades who had failed up against the wall and execute them, we also never spoke about it, nor will we ever speak about it. Let us thank God that we had within us enough self-evident fortitude never to discuss it among us, and we never talked about it. Every one of us was horrified, and yet every one clearly understood that we would do it next time, when the order is given and when it becomes necessary.

I am now referring to the evacuation of the Jews, to the extermination of the Jewish people.[18]

http://en.wikipedia.org/wiki/Holocaust_denial

Just because it is history (and in the books) doesn't mean that it was inevitable or had to happen.

In WWII there were several opportunities where different decisions could have been made and more saved (1938 Evian, 1943 Bermuda)