Newton's First Law of Motion says "an object at rest will remain at rest and an object in motion will remain in motion". This is true __________.

a) only when there is a net force acting on the object

b) only when there is no net force acting on the object

c) when only gravity acts on the object

d) only on falling objects

I think the answer is b because when there is no force acting on the object the object is at rest. Will you explain this question?