Hello!
The answer is:
The first option,

Why?
To find the inverse of a function, we need to rewrite the variable "x" with "y" and the variable "y" with "x", and then, isolate "y".
We are given the function:

Write "f(x)" is equal to write "y", so:

Now, finding the inverse, we have:

Hence, we have that the answer is the first option,

Have a nice day!