A piece of copper and the other of germanium are cooled from the room temperature to 80 K, then which of the following would be a correct statement
(a) Resistance of each increases
(b) Resistance of each decreases
(c) Resistance of copper increases while that of germanium decreases
(d) Resistance of copper decreases while that of germanium increases
(d) Resistance of conductors (Cu) decreases with decrease in temperature while that of semi-conductors (Ge) increases with decrease in temperature.