Three wires P, Q, and R are made of the same metal.
• Wire P has length l and diameter d.
• Wire Q has length 2l and diameter d.
• Wire R has length l and diameter 2d.
Rank the wires by resistance from smallest to largest.
(a) R<P<Q
(b) P<Q<R
(c) Q<P<R
(d) P<R<Q