Motion

question 1 options:

a change in speed over a certain amount of time.

a change in position over a certain amount of time.

a change in direction.

a reference point.

By definition, motion is the change of position over time. The obvious answer would be 

A change in position over a certain amount of time.

If we investigate the choices, the first one talks about acceleration. That is delta velocity over delta time. The third choice is simply distance. And the fourth one is just a point in space used as a reference.

I hope I was able to explain it clearly :)