Answer:
I'd say that it was the assassination.
Step-by-step Explanation: I had a test similar to this, and it was the assassination.
A) excessive speculation and buying on margin
Jimmy Carter is known to be an American politician as well as the 39th President of the United States. During his presidential campaign, he asked the Americans to cast their votes for him for the reason that he could restore that faith of the Americans in their government after the incident of Watergate scandal. The answer is option D.