The correct answer is option B, that is, active transport.
Explanation:
In order to move a substance against an electrochemical gradient or concentration gradient, a cell needs energy. Thus, for this a cell follows active transport mechanisms, for this, energy is expended in the form of ATP in order to sustain the appropriate concentrations of molecules and ions in the living cells.
The active transport refers to the phenomenon in which the movement of molecules or ions takes place through a cell membrane from the region of lower concentration to a region of a higher concentration, facilitated by the enzymes and the process requires energy in the form of ATP.
