If the height of a cylinder becomes of the original height and the radius is doubled, then which of the following is true?

according to the question,

Curved surface area of cylinder having radius (r) and the height (h).

Curved surface area of cylinder = 2πrh

And the new curved surface area of cylinder having radius (2r) and the height(h)

And the new curved surface area of cylinder = 2π × 2r × = πrh

Then, multiplying and divide by 2

= × 2πrh

New curved surface area of cylinder = × original curved surface area.

And the answer is (c).