阅读下列短文，根据短文内容，从题中所给的A、B、C、D四个选项中，选出最佳答案。

The main goal of volunteering is to help others. But it turns out volunteers also benefit(对……有益)from their activities. Allan Luks is one of the leaders of research on the health benefits of kindness. He led the first research which connected the emotion(情感) with physical health benefits achieved by those who regularly help others. The study that Allan Luks conducted of 3，000 volunteers has proven volunteering is good for both the body and mental health.