Which best illustrates active transport?

Group of answer choices

Sodium ions are pumped from a region of lower concentration to a region of higher concentration in the nerve cells of humans.

Glucose molecules move into animal cells through membrane proteins from a region of higher concentration to a region of lower concentration.

Food coloring molecules spread out in a cup of water when a drop of dye is added to the solution.

Water molecules move into red blood cells placed in pure water causing them to swell and burst.

Active transport is a kind of transport in which substances or molecules are moved from a region where they are in low concentration to a region where they are in high concentration. Active transport occurs against concentration gradient, hence, energy input in form of ATP is required.

Based on this description, the option that best ilustrates active transport is when: Sodium ions are pumped from a region of lower concentration to a region of higher concentration in the nerve cells of humans. The process will require energy to occur since sodium ions are pumped against concentration gradient.