The Bronsted-Lowry theory defines an acid as a substance that can donate a proton ( H+ion), and a base as a substance that can accept a proton. For the given chemical reaction: HCl(aq)+H2O(l)⇌H3O(aq)++Cl(aq)− In this reaction, hydrochloric acid (HCl) donates a proton to water (H2O), which acts as a base and accepts the proton, forming hydronium ion (H3O+)and chloride ion (Cl−). Here is the role of each species according to the Bronsted-Lowry theory: HCl is a Bronsted-Lowry acid because it donates a proton to water. H2O is a Bronsted-Lowry base because it accepts a proton from HCl. H3O+is the conjugate acid formed after H2O accepts the proton. Cl−is the conjugate base formed after HCl donates the proton. According to these roles, the correct option identifying the base that accepts a proton in this reaction is: Option B: H2O(l)