A function is a relation that associates one single output for each input value. The first term (the one on the left) of each ordered pair represents the input, and the second represents the output.
Since there's exactly one output associated with each input, this relation is a function.
Notice that, if there were different ordered pairs with the same input, they would need to have also the same output for the relation to be a function.
Therefore, the correct answer is:
Yes, this relation is a function.