According to the Bronsted-Lowry definition,

an acid is a proton acceptor

a base is a proton donor

a base produces H+ ions in aqueous solutions

a base is a proton acceptor

The correct answer is 'a base is a proton acceptor .'

Explanation:

According to the Bronsted-Lowry conjugate acid-base theory:

An acid is defined as a substance which looses or donates protons and forms conjugate base.

        Acid → + Conjugate base

A base is defined as a substance which accepts protons and forms conjugate acid.

       Base + →  Conjugate acid

According to the question the correct answer is 'a base is a proton acceptor.

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