Answer:
The correct option is 4.
Explanation:
From the given graph it is clear that the coordinates of points are A(1,-5), B(0,-2), C(1,0), D(2,3), E(1,5).
It means the given relation is defined as

The set of input values (x-values) is called domain.
The input values of the given relation are 1, 0, 1, 2, 1. A set contains distinct element, so the set of input values is
Input

Domain of the relation is

Therefore the correct option is 4.