Correct option is C
The sum of money increased from 1 to 41/40.
Increase = (41/40) - 1 = 1/40
Since the increase happened in 1/4 year (or one quarter), the quarterly interest rate is also 1/40.
According to question-
Annual interest rate = (1/40) x 4 x 100 = 10%
at a particular rate of simple interest, then the annual rate of interest is: