The force of gravity between two objects is:
F = G*m1*m2/r^2
So, it is dependent of the two masses and the distance between their centers of mass.
C, velocity I believe this is the answer to your question
To solve this problem we will use the definition of the kinematic equations of centrifugal motion, using the constants of the gravitational acceleration of the moon and the radius of this star.
Centrifugal acceleration is determined by
Where,
v = Velocity
r = Radius
From the given data of the moon we know that gravity there is equivalent to
While the radius of the moon is given by
If we rearrange the function to find the speed we will have to
The speed for this to happen is 1.7km/s