Answer:
A.
Explanation:
in order for a function to be a function, one input must only have one output.
We see that in option B, -1 has two outputs (10, 18)
In option c, we see that -4 has two outputs (2, -2)
In option D, we see that -3 has two outputs (5, 0)
This means A is the correct option because each input has only one output.