The answer is D, "appealing to Southern Conservatives by limiting Great Society Programs"
Why?
This was part of Nixon's "Southern Strategy". Included in this was his own pledge to limit the enforcement of existing Civil Rights laws on a Federal level. However, while this was not a direct attempt to make any party members switch allegiances, it was a successful attempt to coax Conservative Democrats (why is that a thing?) to vote for the Republican candidate. This trend also accelerated in the 1980's.
I hope this helps! :D