$f(A,B,C,D)=Π(2,3,5,9,11,12,13)=Σ(0,1,4,6,7,8,10,14,15) $
There are $7$ Prime implicants, among them, there are $2$ EPIs closed in green rectangles and remaining $5$ are non-essential Prime Implicants which are pointed by red arrows.
P = Prime Implicants = 7, Q = Essential Prime Implicants = 2
$\text{Q%P} = \text{2%7}=2$ Hence, 2 is the correct answer.