At a certain grocery store, \(a\) customers each spend an average of \$30 every \(b\) hours. In dollars, how much do customers spend at this store in \(c\) hours?
(A)\(\frac { 30c } { ab } \) (B)\(\frac { bc } { 30a } \) (C)\(\frac { 30bc } { a } \) (D)\(\frac { 30ac } { b } \) (E)\(\frac { 30b } { ac } \)
D