Choose the best topic sentence for this cause-and-effect paragraph. It's complete except for the topic sentence. First, of course, was a natural graying process that came with age. Second was a long period when I worked very stressful jobs. And the third was a period when I was mourning the extremely poor 2005 – 2006 season of the New York Knicks. Add up those three, and gray hair's the result.

A.
I believe I got gray hair as a result of three reasons.

B.
When I developed gray hair, it really helped my professional life.

C.
Gray hair is very attractive.

D.
A lot of people don't like gray hair, but I do.