Mithra Is an Unknown Planet That Has Two Airless Moons

Multiple Choice

$\begin{array} { | c | c | c | c | c | } \hline & \text { Mass } & \text { Radius } & \text { Orbital radius } & \text { Orbital period } \\\hline \text { Moon A } & 4.0 \times 10 ^ { 20 } \mathrm {~kg} & \text { unknown } & 2.0 \times 10 ^ { 8 } \mathrm {~m} & 4.0 \times 10 ^ { 6 } \mathrm {~s} \\\hline \text { Moon B } & 1.5 \times 10 ^ { 20 } \mathrm {~kg} & 2.0 \times 10 ^ { 5 } \mathrm {~m} & 3.0 \times 10 ^ { 8 } \mathrm {~m} & \text { unknown } \\\hline\end{array}$
Mithra is an unknown planet that has two airless moons, A and B , in circular orbits around it. The table summarizes the hypothetical data about these moons. If you dropped a laser at the surface of Moon B, at what rate would it accelerate toward the ground? $\left( G = 6.67 \times 10 ^ { - 11 } \mathrm {~N} \cdot \mathrm { m } ^ { 2 } / \mathrm { kg } ^ { 2 } \right)$

A) $0.25 \mathrm {~m} / \mathrm { s } ^ { 2 }$
B) $0.10 \mathrm {~m} / \mathrm { s } ^ { 2 }$
C) $0.30 \mathrm {~m} / \mathrm { s } ^ { 2 }$
D) $0.15 \mathrm {~m} / \mathrm { s } ^ { 2 }$
E) $0.20 \mathrm {~m} / \mathrm { s } ^ { 2 }$