Which of the following sentences punctuates the appositive or appositive phrase correctly?
A. My friend, who is much older than me, helps me a lot with my homework.
B. My friend who is much older than me, helps me alot with, my homework.
C. My friend who is much older than me, helps me alot with my homework.
D. My friend, who is much older than me helps me alot with my homework.