Answer:
last option is correct.
Explanation:
A relation is a function if each x value has a unique y value.
We'll use this concept to check whether the relation is a function or not.
For the first relation,
the x value 2 has two different values -9 and 8 . Hence, it is not a function.
For the second relation,
the x values -8 and 1 has different y values . Hence, it is not a function.
For the third relation
The x value -5 has different y values. Hence, it is not a function.
For the fourth relation
All the x values have unique y values. Hence, from the definition it is a function.
Therefore, last option is correct.