Which relation is a function? A. \( (-1,4),(0,1),(1,-2),(2,-5) \) B. \( (0,0),(1,1),(2,1),(2,2) \) D. \( (-2,0),(0,-2),(0,2),(2,4) \)

In mathematics, a relation is considered a function if each input (or x-value) is associated with exactly one output (or y-value). This means that no two ordered pairs can have the same first element with different second elements. Looking at the options, option A has all unique x-values, making it a function. Option B fails the function test because the input value \(2\) corresponds to two different outputs (1 and 2). Option D also fails because it has the input \(0\) paired with both \(-2\) and \(2\). Hence, option A is the only relation that qualifies as a function!