Answer:
OPTION C
Step-by-step explanation:
An element in the domain should be mapped to exactly one element on the co-domain. Also, every element in the domain should be mapped to an element in the co-domain.
These two conditions are satisfied to call a relation, a function.
Two different elements in the domain can be mapped to the same element in the co-domain. But the same element in the domain cannot be mapped to two different elements in the co-domain.
A) (1,2), (3,4), (5,6), (3,-4)
Here, the element '3' is mapped to 4 and -4. So, this is not a function.
B) (8,4), (4,3), (2,2), (8,1)
'8' is mapped to 4 and 1. So, it is not a function.
C) (2,5), (3,10), (4,15), (5,20)
All the elements in the domain are mapped to an element in the co-domain. Also, every element in the domain has exactly one image in the co-domain. So, this relation is a function.
D) (2,4), (2,3), (2,1), (2,0)
The element '2' has more than one image. Clearly, it contradicts the definition of a function.
So, only OPTION C is the answer.
