•Question 3 
  Newton concluded that some force had to act on the moon
 because
   
  a.the moon moved at a constant velocity.   
 •b.a force is
 needed to pull the moon outward.   
 •c.a force is needed to pull the moon away from straight-line motion.   
 •d.a force is
 needed to keep the moon in motion.   
 •e.all of the
 above.