Why does an object in motion stay in motion unless acted on by an unbalanced force?
A) because forces are what stop and start motion
B) because balanced forces cannot exist in nature
C) because motion is the inherent state of all matter
D) because motion, once begun, continues to accelerate

because forces are what starts and stops motion.. (a)

Explanation:

as stated in Newton's first law of motion which states that all objects in the world will continue to be in motion or in equilibrium unless acted upon by an external force

28. evolution

29. environment, survive, offspring  

explanation:

prolly a beacuse the momentuem the car has increases while going down hill