According to the Brønsted-Lowry theory, how are acids and bases defined?

The Brønsted-Lowry theory defines acids and bases in terms of proton transfer. According to this theory, acids are substances that donate protons (H⁺ ions), while bases are those that accept protons. This definition expands the understanding of acids and bases beyond just their chemical composition or physical properties, focusing instead on their role in chemical reactions, particularly in aqueous solutions.

For example, when hydrochloric acid (HCl) is dissolved in water, it donates a proton to water, forming hydronium ions (H₃O⁺) and chloride ions (Cl⁻). In this case, HCl is acting as a Brønsted-Lowry acid. Conversely, when ammonia (NH₃) is mixed with water, it accepts a proton from water, producing ammonium ions (NH₄⁺) and hydroxide ions (OH⁻). Here, ammonia functions as a Brønsted-Lowry base.

The other options either define acids and bases based on different criteria or concepts outside of the Brønsted-Lowry framework. Therefore, the focus on proton transfer in option B is fundamental and accurately reflects the essence of the Brønsted-Lowry