Answer:
A. Active transport is the correct answer.
Step-by-step explanation:
Active transport requires the use of energy to move a molecule across a cell membrane.
Active transport is a process in which molecules move against the concentration gradient.
To move the molecules from the lower concentration region to the higher concentration region active transport use energy in the form of Adenosine Triphosphate(ATP).
ATP gives the needed energy for the active transport process to move the molecules across the cell membmbrane or concentration gradient.
Sodium potassium pump is a type of active transport it uses energy to transport the sodium ions and potassium ions inside and outside of the cells.