Correct Answer - B
`-(df)/(Kf^(3))=dt" "," "-underset(f_(0))overset(f)(int)(df)/(Kf^(3))=underset(0)overset(t)(int)dt" ", " "-(1)/(K)underset(f_(0))overset(f)(int)f^(-3)df=timplies (1)/(2K)[(1)/(f^(2))-(1)/(f_(0)^(2))]=t`
`(1)/(f^(2))=(1+2f_(0)^(2)Kt)/(f_(0)^(2))" "," "f=(f_(0))/(sqrt(2f_(0)^(2)Kt+1))`