Answer:
A. It receives a hydrogen ion.
Explanation:
The Bronsted lowry theory of acids and bases solves this problem. The theory states that;
Any compound that can transfer a proton to any other compound is an acid, and the compound that accepts the proton is a base. A proton is a nuclear particle with a unit positive electrical charge; it is represented by the symbol H+ because it constitutes the nucleus of a hydrogen atom.
So among the options, the option that says a base receives a hydrogen ion is the right answer which is option A.
Take the following reaction for example:
HCl + NH₃ ⇌ NH₄⁺ + Cl⁻
Hydrochloric acid (HCl) is the Brønsted-Lowry acid because it donates a hydrogen ion. Ammonia (NH3) is the Brønsted-Lowry base because it accepts the hydrogen ion.