If two ends of rods of length L and radius r, made of same material are kept at the same temperature difference, which of the following rods conduct most heat per unit time?

A

L = 50 cm, r = 11 cm

B

L = 2 cm, r = 0.5 cm

C

L = 100 cm, r = 2 cm

D

L = 3 cm, r = 1 cm