Given the question: Write a multi-choice question for the following article: Article: I work as a volunteer for a group that helps the poor in Haiti. I decided to take my son Brain there for a week, hoping to educate him. Before getting out, I told Brain this trip would be tiring and hard. For the first two days, he said almost nothing. Then on the third day, when we were climbing over high rocky mountains , he turned to me and smiled, "Really hard." After that, a five-year-old girl, wearing a too large dress and broken shoes, followed Brain around. Later he said, "I wish I could speak French." I was surprised that this was from a boy who always hated French classes. However, the moment that really reached my heart _ in a village in the mountains. I was interviewing a woman villager for an article. By working hard, she learned to read and write and became one of the leaders of the village. Learning her story, Brain was greatly touched. His eyes were wet and there was love and respect on his face. He finally understood the importance of my work. When leaving for home, Brain even offered to stay in as a volunteer. This trip was very meaningful.
The answer is:
Question: What is the passage mainly about?Options:A An exciting trip.B How to be a volunteer.C A story of a volunteering trip.D The importance of voluntary work.Answer:C