The Weight of Spaceman Speff at the Surface of Planet

Multiple Choice

The weight of spaceman Speff at the surface of planet X,solely due to its gravitational pull,is 389 N.If he moves to a distance of 1.86 × 10⁴ km above the planet's surface,his weight changes to 24.31 N.What is the mass of planet X,if Speff's mass is 75.0 kg? (G = 6.67 × 10^-11 N ∙ m²/kg²)

A) 2.99 × 10²⁴ kg
B) 2.99 × 10¹⁸ kg
C) 2.99 × 10¹⁷ kg
D) 1.59 × 10¹⁸ kg