A scalar function is defined as:
'A function from a set X to a set Y assigns to each element of X exactly one element of Y. The set X is called the domain of the function and the set Y is called the codomain of the function.'
Therefore, if we have the following function

Given the x, y is unique.
The inverse function, takes the function value to its corresponding x value.

In our problem, we have the following function values

If we apply the inverse function on all of those values, we should get the argument of the function back.

Therefore, from the possible answers, only (1, 4) belongs to the inverse.