Option D:
are the ordered pairs represents a function.
Explanation:
Given that the options of the set of ordered pairs.
We need to determine the ordered pairs that represents a function.
Option A: 
A relation is said to be a function if each element of x is related to exactly one element in y.
From this set of ordered pairs, it is obvious that the element -12 of x is related to two different element in y.
Thus, the ordered pairs
is not a function.
Hence, Option A is not the correct answer.
Option B: 
From this set of ordered pairs, it is obvious that the elements -8 and 8 of x are related to two different element in y.
Thus, the ordered pairs
is not a function.
Hence, Option B is not the correct answer.
Option C: 
From this set of ordered pairs, it is obvious that the element 13 of x is related to three different element in y.
Thus, the ordered pairs
is not a function.
Hence, Option C is not the correct answer.
Option D: 
A relation is said to be a function if each element of x is related to exactly one element in y.
From this set of ordered pairs, it is obvious that the each element of x is related exactly one element in y.
Thus, the ordered pairs
is a function.
Hence, Option D is the correct answer.