Heat is flowing through two cylindrical rods of the same material. The diameters of the rods are in the ratio 1 : 2 and their lengths are in the ratio 2 : 1. If the temperature
difference between their ends is the same, then the ratio of the amounts of heat conducted through them per unit time will be:

• A

  1 : 1

• B

  2 : 1

• C

  1 : 4

• D

  1 : 8