A pendulum clock loses 12 s a day if be the temperature is `40^(@)C` and gains 4 s a day if the temperature is `20^(@)C`. The temperature at which the clock will show correct time and the coefficient of linear expansion `alpha` of the pendulum shaft are, respectively
A. `60^(@)C, alpha=1.85 xx 10^(-4)//""^(@)C`
B. `30^(@)C, alpha=1.85 xx 10^(-3)//""^(@)C`
C. `55^(@)C, alpha=1.85 xx 10^(-2)//""^(@)C`
D. `25^(@)C, alpha=1.85 xx 10^(-5)//""^(@)C`
