Why was the 1968 election a turning point in US political history?

A.
It saw the end of the New Deal coalition.
B.
It saw the first important third-party candidacy.
C.
It saw the Republican Party become dominated by eastern moderates.
D.
It saw the South swing to the Democratic Party.

Explanation:

The 1968 presidential election took place against civil unrest and tragedy, following the assassinations of Robert Kennedy and Martin Luther King Jr. Race riots and the ongoing Vietnam War had shaped public perception negatively against the incumbent Johnson administration.

after the civil war, and with the termination of slavery, the south was faced with a big problem; what was supposed to happen and how they were supposed to deal with the freedom and the rights that black people and freed slaves had gained as a result of the north defeating the south and forcing the end of slavery. first, most, if not all, of the workforce of the south came from slaves and they did not have an option to replace the loss of said workforce. second, particularly in the south, people were convinced that black people were lesser, less intelligent, less capable and less smart than whites. this posed a huge problem for them. also, southerners were faced with another issue; freed slaves now had a say in how their lives would be lived and the right to politically choose the way they would be governed. people in the south did not want to accept this, none of this and this opposition and the conflicts that arose from it, not to mention the afereffects of the war, forced the congress of the time to enact and enforce the reconstruction plans that had been proposed by president andrew johnson.