Answer:
Option 1
Explanation:
A relation is a series of related x values which map to y values. A function has x values which map to one and only one y value each. In other words, a function cannot have X values repeating and mapping to other y values.
In option 2, -7 repeats in the (x,y) pairs with different y values.
In option 3, 1 repeats in the (x,y) pairs with different y values.
In option 4, -2 repeats in the (x,y) pairs with different y values.
Only option 1 meets the requirement.