A clock which keeps correct time at $20^{\circ} \mathrm{C}$ has a pendulum rod made of brass. How many seconds will it gain or lose per day when temperature falls to $0^{\circ} \mathrm{C}$ ? $\left(\alpha=18 \times 10^{-6}{ }^{\circ} \mathrm{C}^{-1}\right)$
(a) $155.5 \mathrm{~s}$
(b) $15.55 \mathrm{~s}$
(c) $25.55 \mathrm{~s}$
(d) $18.55 \mathrm{~s}$