Which is a Function and which isn't a Function

I believe  that A is the function to this problem

Step-by-step explanation:

1 - A is not a function

2 - B is not a function

3 - A is not a function

X can have only 1 value

for example 2B features x=5 where f(x) = -4 but also 1. That means it's not a function

(1,4) is on graph of f(x)

f(1) = 4

so 1/4 f(x)

1/4 f(1)

1/4. ×4

1

so point for function 1/4. f(x) is (1,1)