Answer:
Table 2
For every input, there is one output.
Why table 1 is not a function:
The input 5 has two outputs, 3 and 2
Why table 3 is not a function:
The input 1 has two outputs, 2 and 3
Why table 4 is not a function:
The input 4 has three outputs, 2, 3, and 4
Hope this helps!