In this question, we will have to test each answer choice. The final volume is approximately doubled.
Imagine $initial volume = pi * R^2 * H$. Hence $final volume = 2 * pi * R^2 * H$. We need to find which answer choice is farthest from the final volume.


R will become 2R, H will become (0.5)H. Plugging in these values, we find that $pi * 2^2*R^2 * (0.5)H = 2 * pi * R^2 * H$. Exactly the final volume. Eliminate.


Similarly, new radius = (0.7)*R, new height = 4*H. New volume is a $(0.7)^2 * 4 = 0.49 * 4$ multiple of initial volume. Close to double the initial volume. Eliminate.


Again, new radius = (0.9)*R, new height = (2.5)*H.$New multiple = (0.9)^2 * 2.5$, coming slightly greater than 2. Eliminate.


Similarly, new radius = (1.4)*R, new height = H. $New multiple = (1.4)^2 = 1.96$, coming not very close to 2. Hold to compare.


New radius = (1.5)*R, new height = (0.8)*H. $New multiple = (1.5)^2 * (0.8) = 1.8$, coming farthest from 2 so far.

Hence, E is the correct answer.