Given that
There is a cylinder and we have to find the change in its volume if the radius is doubled and the height is halved.
Explanation -
Let the Initial radius be r and the height be h. Then the initial volume will be
[tex]v=\pi\times r^2\times h-----------(i)[/tex]Now applying the given changes,
new radius = 2 x r
new height = h/2
Then the new volume will be V,
[tex]\begin{gathered} V=\pi\times(2r)^2\times\frac{h}{2} \\ \\ V=\pi\times4r^2\times\frac{h}{2} \\ \\ V=2\times\pi\times r^2\times h \\ \\ On\text{ substituting v = }\pi\times r^2\times h \\ \\ V=2\times v \end{gathered}[/tex]Hence volume will be doubled. And option D is correct.
Final answer -
Therefore the final answer is OPTION D.