Answer:
The correct option is A) ATP
Explanation:
Some ions or molecules tend to move in the cell along a concentration gradient. Such types of movement is known as passive transport. In passive transport, molecules move from a higher concentration to a lower concentration. Such kind of movement doesn't require energy.
Other kinds of molecules or ions move against the concentration gradient i.e from a lower concentration to a higher concentration. Energy is required for these process to occur.The energy used is in the form of ATP.
