For Each Paragraph Below, Select the Number of the Topic

For each paragraph below, select the number of the topic sentence. Identify the topic sentence of the paragraph below.
(1) Volunteering doesn't just benefit those who receive help; it significantly improves the health and happiness of the volunteer, too. (2) According to several studies, elderly people who volunteer are less depressed and more physically healthy than elderly people who don't volunteer. (3) Plus, those same studies found that the volunteers lived longer. (4) However, it's not just senior citizens who benefit from volunteering. (5) The connection between volunteering and good health is so strong, as a matter of fact, that the Public Health Center at Harvard University created a media campaign to encourage new retirees to sign up to volunteer. (6) Child psychologists say that volunteer work helps adolescents and teenagers, too, by building their self-esteem and socialization skills.

A) Sentence 1
B) Sentence 2
C) Sentence 4