Explanation

(c) We know that resistance of conductor is directly proportional to temperature ($ie$, $R \propto \mathrm{\Delta}t$), while resistance of semiconductor is inversely proportional to temperature $\left( ie,\ R \propto \frac{1}{\mathrm{\Delta}t} \right)$.
Therefore, it is clear that resistance of conductor decreases with decrease in temperature of $vice$-$versa,$ while in case of semiconductor, resistance increase with decrease in temperature of $vice$-$versa.$
Since, copper is pure conductor and germanium is a semiconductor hence, due to decrease in temperature, resistance of conductor decreases while that of semiconductor increases.