Please help! An astronaut orbits planet X in his spaceship. To remain in orbit at 675 km above the planet's center, he maintains a speed of 76 m/s. What is the
mass of planet X? Note: the constant of universal gravity (G) equals 6.674 X 10 ^-11 N m^2/kg^2.
A. 7.7 x 10^14 kg
B. 5.8 x 10^19 kg
C. 7.7 x 10^17 kg
D. 5.8 x 10^16 kg