A planet of mass m moves around the sun of mass M in elliptical orbit. The maximum and minimum distances of the planet from the sun are `r_1` and `r_2` respectively. The time period of the planet is proportional to

Options

A. `(r_1 - r_2)^(3/2)`
B. `(r_1 + r_2)^(3/2)`
C. `(r_1 )^(3/2)`
D. `(r_1 )^(2/5)`