Volunteering offers many of the same social benefits, with the added bonus

A. Students at universities must join at least one activity in volunteer campaign at local schools. 

B. Students at universities should join as many activities in volunteer campaign at local schools as possible. 

C. Students at universities who join volunteer work will gain a lot of purposes for the community only. 

D. Students at universities who join volunteer work will gain a lot of purposes for not only themselves but also the community.