Task: Question Answering
Input (English): If \(100 - 2xy - y^2 = x^2\), which of the following must be true?
(A)\(x - y = 10\) (B)\(x^2 + y^2 = 100\) (C)\((x + y)(x - y) = 100\) (D)\((x + y)^2 = 100\) (E)\((x - y)^2 = 100\)
Output (English): D