He believed in making a new "perfect aryan race". Jews didn't fit that description, so he decided to kill them. He killed anybody really, but Jews were his main target as he was very anti-Semitic and blamed them for basically all of the worlds problems.
C
Vice President is the only member in the executive branch that can vote in the Senate to break a tie
B
President Truman declared the US's intervention as "police action" and did not declare war formally.