Answer:
A
Explanation:
1. Active transport is the process of transport of molecules against the concentration gradient with the help of energy.
2. In active transport, a protein pump uses energy( in the form of ATP), and it move molecules from region of low concentration to region of high concentration across a membrane.
3. Example of active transport: The sodium-potassium pump,
The sodium-potassium pump moves sodium ions out of the cell and potassium ions into the cell against their concentration gradient.