Q $75.$ If the allowable error $()$ in the estimation of rainfall is $10$ percent, and coefficient of

variation $)$ is $20$ percent, then the optimum number of rain gauges $(N)$ is

$($A$)N=4$

$($B$)N=1$

$($C$)N=10$

$($D$)N=8$

$($E$)$ Question not attempted