Answer:
The statement that supports Newton's first law of motion is the one that says that planets can move at a varying speed due to forces exerted in space.
Step-by-step explanation:
Newton's first law of motion states that, if no resulting force acts on an object, no change in speed of that object can occur. The speed will therefore remain unchanged: both size and direction of the speed will remain constant. Therefore, the object will remain stationary (speed 0) or move at a constant speed in a certain direction.
The first law is also called the law of inertia: an object on which no external forces work is at rest or performs a unified rectilinear movement. To change the state of motion of an object requires a force.