What characterizes a base in terms of hydrogen ion concentration?

A base is characterized by its ability to reduce hydrogen ion concentration in a solution. This reduction in hydrogen ions leads to an increase in the pH of the solution, which is why bases are often associated with higher pH values (typically greater than 7). When a base is added to a solution, it either donates hydroxide ions (OH⁻) or accepts hydrogen ions (H⁺), both of which result in a lower concentration of hydrogen ions compared to the original state of the solution.

In contrast, options that suggest a base increases hydrogen ion concentration or enhances acidity are misleading, as they describe properties of acids. A neutral pH indicates a balance between hydrogen and hydroxide ions, which applies to water rather than bases. Therefore, the description of a base as one that reduces hydrogen ion concentration accurately reflects its fundamental chemical behavior.