Answer:
A
Explanation:
for the relation to be a function then each value of x in the domain must map to exactly one unique value of y in the range
this is the case for A
in B : 3 → 2 and 3 → 8 ← not a function
in C : - 2 → 5 and - 2 → 7 ← not a function
in D : 2 → 2 and 2 → 3 and 3 → 3 and 3 → 2 ← not a function