What Was the Basis for Isaac Newton's Conclusion That a Force

Multiple Choice

What was the basis for Isaac Newton's conclusion that a force from the Earth must be acting on the Moon?

A) A force is needed to keep the Moon in motion in its orbit.
B) A force is needed to pull the Moon outward.
C) A force is needed to accelerate the Moon toward the Earth, away from straight-line motion.
D) The Moon moved at a constant velocity in a straight line.