C. It is answered by observation and evidence.
Good scientific explanations are defined, measurable and controllable. They can be answered by an experiment.
An atom. Hope this helped
Answer:
Cell Membrane
Explanation:
The cell membrane controls what goes in and out of a cell, and keeps it shape, much like a city limit.
Regardless of what direction an object is moving, the acceleration
due to gravity is always directed toward the center of the Earth.
That's the direction commonly known as "down".
