If a Block Is Set Sliding on a Huge Frictionless

Multiple Choice

If a block is set sliding on a huge frictionless plane in contact with the Earth, it will NOT continue to move at constant speed because

A) gravity will pull in a non-perpendicular direction as the block gets farther out on the plane.
B) of its inertia.
C) gravity gets weaker as distance increases.
D) it is not free from the shackles of Earth's gravity.