A solution that is equal in solute concentration to that of the cytoplasm of a cell and causes a cell to neither lose nor gain water by osmosis is a(n)

isotonic solution

Explanation:

The cell membrane is semi-permeable, so it allows to pass through certain solutes. By a process called osmosis, the water molecules move from a compartment of lower concentration of solutes to a compartment with higher concentration.

Therefore, if the concentration of solutes in the outside is higher than the concentration in the cytoplasm (hypertonic solution), the water molecules will move from the interior to the exterior. Conversely, if the cytoplasm is more concentrated than the outside (hypotonic solution), the water molecules will move from the exterior to the interior. If the cytoplasm has the same solute concentration as the outside, the solution of the outside is called isotonic, and no water net flux will be produced.