GRE Question of the Day (August 25th)

Let f be a function such that f(mn) = f(m)f(n) for every positive integers m and n. If f(1), f(2) and f(3) are positive integers, f(1) < f(2), and f(24) = 54, then what is the value of f(18)?

A. 8
B. 9
C. 10
D. 11
E. 12