A viscous fluid is flowing through two horizontal pipes. The pressure difference P2 - P1 between the

Question:

A viscous fluid is flowing through two horizontal pipes. The pressure difference P2 - P1 between the ends of each pipe is the same. The pipes have the same radius, although one is twice as long as the other. How does the volume flow rate QB in the longer pipe compare with the rate QA in the shorter pipe?
(a) QB is the same as QA.
(b) QB is twice as large as QA.
(c) QB is four times as large as QA.
(d) QB is one-half as large as QA.
(e) QB is one-fourth as large as QA.