Answer:
Identity function
Step-by-step explanation:
We are given the following in the question:
Let f(x) be a function.
Then, inverse of f(x) can be written as:

The composition function of the function and the reverse function can be found as:

which is an identity function.
Thus, the correct answer is
The identity function, f(x) = x, is formed by the composition of a function and its inverse.