The correct answer is B). X
Explanation:
Every function got a set of input values called " Domain " and a set of respective output values as " Range"
And function worked as Function( Input value ) = Output value
There are basic rules for function :
1. There always exist output value for every single input value.
2. Every input value should have one and only one output value
For W :
Rule 2 is violated
Here, Input value 6 result to two output value 2 and 4
For X :
No rule is violated
For Y :
Rule 2 is violated
Here, Input value 6 result to two output value 2 and 6
For Z :
Rule 2 is violated
Here, Input value 7 result to two output value 2 and 8
The correct answer is B). X