The other parts are equal to (a + b)2.is the reasoning for what question and answer pair?
Q: Four of the five parts numbered (a),(b),(c),(d) and (e) in the following equation are exactly equal. Which of the parts is not equal to the other four? The number of that part is the answer.
Options:
(A) (a – b) 2 + 4ab
(B) a(a + b)  + b(a + b) 
(C) (a2 – b2)  + 2b(b + a) 
(D) (a – b) b + (a + b) 2b
(E) (a + b) 2 – 2a(a – b)  + a(2a – 2b) 
A: (D)