Speed = Distance/Time. So you are required to know A. Distance and period of time
The answer would be cell membrane the cell membrane is basically the wall of the cell which forms the cell shape which allows to form animals structure and support
Changes in state of matter would be a physical change to whatever it is that you are changing so I think it would be B.Molecules because in order for something to change the molecules have to be moving apart from one another but I maybe wrong depending on what it is your looking at
Heres one: If you were driving at night, and a car was coming toward you at high speeds, You could tell they were coming because of the increase of sounds and light. Hope this helps!
