A pendulum clock loses 12 s a day if the temperature is $40^oC$ and gains 4 s a day if the temperature is $20^oC$. The temperature at which the clock will show correct time, and the co-efficient of linear expansion ($\alpha$) of the metal of the pendulum shaft are respectively :

Question

( A ) $60^{\circ}; \alpha = 1.85 \times 10^{-4} /^{\circ}C$
( B ) $55^{\circ}; \alpha = 1.85 \times 10^{-2} /^{\circ}C$
( C ) $25^{\circ}; \alpha = 1.85 \times 10^{-5} /^{\circ}C$
( D ) $30^{\circ}; \alpha = 1.85 \times 10^{-3} /^{\circ}C$