Answer:
This is a function because every input maps to only one output
Explanation:
We set x and y values to determine if it is a function or not:
X Y
0 1
1 2
2 1
3 2
4 1
We noticed that none of the values for x is repeated, and each x-value has only one corresponding y-value
Therefore, this is a function because every input maps to only one output.