Answer:
Table D.
Explanation:
According to the laws of a function, one input can not have multiple outputs.
3 - 1
3 - 4
2 - 3
Three has more than one output; 1 and 4.
2 - 7
5 - 6
2 - 9
Two has more than one output; 7 and 9.
1 - 5
7 - 2
7 - 3
Seven has more than one output; 2 and 3.
3 - 4
1 - 5
8 - 5
While i'm not sure what the function is, it has no repeating input-outputs (only outputs). I may not be 100% correct, as i'm taking the test right now in fact, but I certainly hope this is the right answer (for the both of us!) I'll edit my answer if it's indeed incorrect.