If x and y are positive integers and 1 + x + y + xy = 15, what is the value of x + y?
A. 3
B. 5
C. 6
D. 8
E. 9

Please lemme know whether i've solved it correctly..
(x+1)(y+1) = 15
=> x=2, y=4.
=> C answer

OA: C