Question

a substance that helps maintain a constant ph is best described as select select a buffer a solution a base an acid

Explanation:

A buffer is defined as a substance (or a solution containing a weak acid and its conjugate base, or a weak base and its conjugate acid) that resists changes in pH, thus helping to maintain a constant pH. An acid donates protons, a base accepts protons, and a solution is a general mixture, none of which specifically maintain pH like a buffer.

Answer:

a buffer