Which of the following italicized parts indicates CONTRAST？A．He is doing his homework whil

Which of the following italicized parts indicates CONTRAST？

A．He is doing his homework while his dog is playing outside.

B．They used to live in the same building when they were young.

C．While the party won the election, tiiey had lost many votes from lower class.

D．Work hard and you will benefit from it.

请帮忙给出正确答案和分析，谢谢！