Answer is B.
In a day, clock ticks 12’O clock 2 times. In 2 days, clock with strike 12’o clock 4 times.
So, a clock strikes once at one o’clock, twice at two o’clock and twelve times at 12 o’clock, this means (1 + 2 + 3 + … + 11 + 12).
(1 + 2 + 3 + … + 11 + 12) is sum of 12 terms which is in AP. So, sum of the first n terms in an arithmetic sequence is (n/2)⋅(a₁+aₙ).
Here sum = (12/2)*(1+12) = 78
for 2 days, no:of times clock will strikes is 4 * (1 + 2 + 3 + … + 11 + 12) = 4*78 = 312