If a, b, c, and d are positive integers, what is the value of (a + b)(c + d)?

[BTGmoderatorDC]

If a, b, c, and d are positive integers, what is the value of (a + b)(c + d)?

(1) 4*a! = b!
(2) 5*c! = d!


OA C

Source: Manhattan Prep