3 is CORRECT. The ROM contains 2^n x m bits of information. Thus using the capacity formula
C = 2^n x m, we apply values for C and m to obtain
64K = 2^n x 8, or 8K = 2^n.
Since K = 2^10 and 8 = 2^3, then
2^3 * 2^10 = 2^n which implies that
3 + 10 = n
Thus n = 13.