Task: Question Answering
Input (English): If a is a real number, and if \(a^2 - 1 = a + 1\), which of the following could be true? I. \(a = -1\) II. \(a = 1\) III. \(a = 2\)
(A)I only (B)II only (C)III only (D)I and III only (E)I, II and III
Output (English): D