One of newton’s laws of motion states that objects in motion tend to stay in motion. what is the reason that this law may not always prove true for objects on earth?

The answer is D.

The full specification of Newton's First Law is (from Wikipedia)

In an inertial frame of reference, an object either remains at rest or continues to move at a constant velocity, unless acted upon by a force.

On earth we're generally in slightly a non-inertial frame, with rotation and revolution around the sun. It's also impossible to turn of gravity, so objects are being acted upon by an outside force. Typically there's also the outside force of friction, which makes things tend to stop.

a. is correct

it would open into a square depending on the type of envelope i’m not sure about the second part