For any numbers, x and y, \(x \blacksquare y\) is defined as \(x \blacksquare y = x^2 - y\). If \(a \blacksquare b = (a + 2) \blacksquare (b + 2)\), which of the following must be true?
(A)\(a = 0\) (B)\(a = -\frac { 1 } { 2 } \) (C)\(a = -1\) (D)\(b = 0\) (E)\(b = -1\)
B