Answer:
A. The assassination of President Kennedy
Explanation:
President Kennedy tried to propose various social programs during his presidency. He urged for tax cuts, improving education and health care, raising the minimum wage, programs for the elderly, etc. Conservatives were constantly against him, and all he managed was increasing minimum wage and cutting down taxes a bit.
However, his assassination turned the narrative around - suddenly, the time of his presidency was massively seen as positive and he was praised more than ever. The public and political opinion of him changed with that, and conservatives started adopting his social program ideas more.
