Which of the following correctly describes an acid?

An acid is correctly described as a substance that donates protons. In the context of Brønsted-Lowry theory, which is one of the most widely accepted definitions of acids and bases, an acid is defined specifically by its ability to donate protons (H⁺ ions) to other substances during a chemical reaction. This proton donation is a key characteristic that distinguishes acids from bases, which are defined by their ability to accept protons.

The pH scale, which ranges from 0 to 14, is used to quantify the acidity or basicity of a solution. Substances that have a pH less than 7 are considered acidic, with lower pH values indicating stronger acids, while those with a pH above 7 are considered basic. Therefore, stating that an acid has a high pH would be incorrect, as true acids have low pH values.

In terms of electron behavior, acids do not primarily focus on donating electrons; instead, they are characterized by their proton donation. Thus, the definitions relating to electron donation or proton acceptance do not adequately describe the fundamental behavior of acids in this context.