A pendulum clock is made of iron rod $\;(\alpha_{iron}={10^{-5}}^{0}C^{-1})\;.$ At room temperature $\;(15^{0}C)\;,$ it works correctly . The error when the temperature rises to $\;24^{0}C\;$

Question

$(a)\;7.77\;sec\;per\;day\qquad(b)\;77.7\;sec\;per\;day\qquad(c)\;3.88\;sec\;per\;day\qquad(d)\;38.8\;sec\;per\;day$