Grant is a member of a book club. He pays a $10 yearly membership fee and can purchase books through the club for $2.75 each. His total annual cost is a function of the number of books that he purchases in a year.

Let b represent the number of books he purchases in a year. Which function, C(b), represents his yearly cost?
C(b) = 10b + 2.75
C(b)= 2.75b + 10
C(b) = 12.75b
C(b) = 2.75b + 20