Given:
The different relations in the options.
To find:
The relation which represents a function.
Solution:
A relation is called a function if there exist a unique output (y-value) for each input (x-value).
In option A, there exist two outputs y=7 and y=1 for a single input x=-1. So, this is not a function.
In option B, there exist two outputs y=-5 and y=2 for a single input x=-1. So, this is not a function.
In option C, there exist two outputs y=2 and y=4 for a single input x=3. So, this is not a function.
In option D, there exist only one value of y for each x. So, this is a function.
Therefore, the correct option is D.
