Answer:
For an ordered pair (x,y) that a set contain :
x = Domain of the relation
y = Range of the relation
In a relation x can have two or more than two ranges i.e a x can have more or more than two images.
So, Domain = First element of ordered pair that the following relation R contains ={(−3, 4), (5, 0), (1, 5), (2, 8), (5, 10)}= -3, 5, 1,2,5
But the element 5 is Occuring twice.
Domain = { -3,1,2,5} →→Option A