The correct answer for this question is Option D) Peasant farmers.
Mao Zedong himself belonged to a village family and came from a peasant background. He could not only speak their language and connect with them, he understood their problems and what they wanted in life.
Since peasants were the most numerous class of people in China, Mao Zedong understood that the support of the peasants would be instrumental in coming to power.
He used his excellent public speaking skills and pure propaganda to garner support among millions of people in the country side and was eventually able drive out Jiang Jieshi and the Guomindang.