Answer:

g is the input

h is the input

f is the input
Explanation:
Given
See attachment for functions and inputs
Required
Match the function with their inputs
The variables on the left-hand side or the variables inside the function bracket are the inputs of the function. e.g. x is the input of f(x)
Using the above description, we have:

g is the input

h is the input

f is the input