What are buffers?

Proteins are macromolecules composed of amino acids that perform a variety of functions in biological systems, including acting as enzymes, structural components, and signaling molecules. While some proteins can act as buffers (like hemoglobin), they are not universally classified as buffers themselves. Therefore, this choice does not accurately define what buffers are.

Catalysts are substances that speed up chemical reactions without being consumed in the process. They lower the activation energy required for reactions to occur but do not influence the pH stability of a solution. Thus, this choice does not pertain to the definition of buffers.

Inhibitors are agents that decrease the rate of a reaction or prevent it from occurring altogether. They function in a very different role compared to buffers, which are focused on stabilizing pH rather than altering reaction rates. This choice is therefore unrelated to the concept of buffers.