The correct statement about the reaction is:
HCl is an acid, and Cl– is its conjugate base.
In the reaction, HCl donates a proton (H+) to water (H2O), making HCl the acid. The product Cl– is the conjugate base of HCl after it donates the proton. H2O acts as a base in this reaction, producing H3O+ (the hydronium ion) as it accepts the proton.