Acylinder and a cone are shown below.

For this case we have that the volume of a cylinder is given by:

And the volume of a cone is given by:

Where:

A: It's the radio

h: It's the height

In this case:

And the height is the same for both.

For the area of the bases to be equal, the volume of the cylinder must be 3 times the volume of the cone.

It is observed that:

Then, it is not fulfilled.

Option D

For any point (x, y), that appears in one function, the point (y, x) must appear in the other function.  

For any point (x, y), that DOESN'T appear in one function, the point (y, x) must NOT appear in the other function.  

So if you find any point that DOESN'T meet the above rules, you can prove that the functions are NOT inverses of each other.  

But if you want to prove that they ARE inverses of each other, you have to check ALL points in the functions, and there are infinity of them, so that's not practical. Instead, you can write f(x) like this:  

y = 3x - 5  

Now solve for x:  

y + 5 = 3x  

x = (y + 5) / 3  

Now swap x and y:  

y = (x + 5) / 3  

This is the same as g(x). Therefore the functions are inverses of each other.

Step-by-step explanation: