Given:
There are given that the diameter of a cylinder is 4m.
Step-by-step explanation:
The diameter of the cylinder is given 4 m.
Then,
We need to find the value for the radius.
So,
From the formula of the radius:

Then,
Put the value of d into the above formula:
Then,

Now,
According to the question:
The value of height is triple the radius.
So,
The length is:

Now,
From the formula of volume of the cylinder:

Then,

Final answer:
Hence, the correct option is D.