Let P(n) and S(n) denote the product and the sum, respectively, of the digits of the integer n. for example, P(23)=6 and S(23)=5. Suppose N is a two-digit number such that N=P(N)+S(N). What is the unit digit of N ?
(A) 2 (B) 3 (C) 6 (D) 8 (E) 9
ANSWER:E