What are the inputs of the following function?
{(-3, 2), (-4, 2), (8,3), (7, 1)}
A. {-4, -3, 7, 8}
B. {1, 2, 3, 7, 8}
C. {1, 2, 3}
D. {-4,-3, 1, 2, 3, 7, 8}
