P and Q are two sets such that n(P) = 5 and n(Q) = 3. A relation from P to Q is selected at random. Then the probability that the relation is not a function is

A

$$\frac{2^{15} - 5^3}{2^{15}}$$

B

$$\frac{2^{15} - 3^5}{2^{15}}$$

C

$$\frac{3^5}{2^{15}}$$

D

$$\frac{5^3}{2^{15}}$$