Marvin eats 3 bananas and 1 apple every day. If the cost of each banana is b dollars and the cost of each apple is a dollars, which of the following represents the total cost, in dollars, of the bananas and apples Marvin eats in 1 week? (1 week = 7 days).
(A)\(7b + a\) (B)\(21b + a\) (C)\(7(b + a)\) (D)\(7(b + 3a)\) (E)\(7(3b + a)\)
E