Ulysses S. Grant was not considered a popular president, even though he had been a popular war hero. Which statement describes why?

A. He refused to work with Radical Republicans in Congress.
B. His ability to lead was marred by scandal.
C. He took a strong stand against Southern resistance to Reconstruction.
D. He oversaw a long period of economic growth and prosperity.

I thought the answer was C but that was wrong so is B correct?