The mass density of a planet of radius R varie with the distance r form its centre as `rho (r) = p_(0) ( 1 - (r^(2))/(R^(2))) `. Then the graviational field is maximum at :

Options

A. ` r = sqrt((5)/(9))R`
B. ` r= (1)/(sqrt(3)) R`
C. `r = R`
D. ` r = sqrt((3)/(4))R`