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.\nOptions:\n(A) (a – b) 2 + 4ab\n(B) a(a + b)  + b(a + b) \n(C) (a2 – b2)  + 2b(b + a) \n(D) (a – b) b + (a + b) 2b\n(E) (a + b) 2 – 2a(a – b)  + a(2a – 2b) 
Please answer the following question by reasoning step-by-step.
(D)
The other parts are equal to (a + b)2.

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Thus, the answer is (D)