f(x) = 4x + 3
That's one-to-one, a linear function that will give a different f(x) for each different x.
For the inverse let's swap x and y and solve for y
x = 4y + 3
x - 3 = 4y
y = (x- 3)/4
That's the inverse,
Answer: (x- 3)/4, second choice
The domain and range of the inverse is all real numbers. It's two lines; I'll leave the graphing to you.