Answer:
D. It split the vote of the Democratic party,
Explanation:
The main effect of the presidential campaign of Martin Van Buren in 1848 is that "It split the vote of the Democratic party."
This is evident in the fact that Martin Van Buren who was a former President of the United States, campaigned under the Free soil party after Lewis Cass was given the nomination to run for President under the Democratic party. This is to show the power of the anti-slavery movement, and assists in defeating Lewis Cass.
Eventually, Martin Van Buren was able to split the Democrat vote causing the Whig candidate, Zachary Taylor to win the election of 1848
