Option D is correct.
The relation {(-8, -6) (-5, 2) (-8, 1) (7, 3)} is not a function.
Explanation:
Given the relation: {(-8, -6) (-5, 2) (-8, 1) (7, 3)}
Domain is the set of all possible inputs of a relation i.e { -8, -5 , -8 , 7}
Range is the set of output values of a function i.e, {-6, 2 , 1 , 3}
The mapping as shown below in the figure:
A function is a relation in which every element of the domain is matched to not more than one element of the range.
In other words, we can say that ,no value of x gets mapped to more than 1 value of y.
Since, from the mapping you can see that the domain value -8 paired with -6 and 1; as x is used more than once.
Therefore, this relation is not a function