A fine needle is being used to deliver a drug to a patient over a certain time. Which ONE of the following arrangements, if made alone, would deliver twice the volume of drug?
(A) Double the length of the needle.
(B) Increase the time of delivery by 50%.
(C) Halve the pressure difference between the ends of the needle.
(D) Increase the radius by 19%.
(E) Decrease the diameter by 36%.