Step-by-step explanation:
A relation is a function if and only if for each value of x there's only one value of y. In other words, if we find one value of x more than once, the relation is not a function.
Relation A is not a function because x = 2 shows up twice: (2, 5) and (2, 7)
Relation C is not a function because x = 1 shows up three times: (1, 3), (1, 5) and (1, 7)
Relation E is not a function because x = 2 shows up twice: (2, 5) and (2, 1)
Relations B and D have only one time each value of x
Answers: