800 J Got it right on edgenuity
I believe the answer is B. that's where the asetroid belt is.
The radius of the cylinder is equal to half the diameter:

The volume of the cylinder is given by:

where h is the heigth of the cylinder. Converting into meters,

And the density of the material will be given by the ratio between the mass and the volume:

Gravity lets all objects fall to the ground at the same speed, 9.8 m/s/s. If the force of gravity were stronger, such as 10 m/s/s, the rate of acceleration would be faster.