Answer: Option B) Base
Step-by-step explanation:
According to Bronsted-Lowry theory, an acid is a substance that donates a proton and produces a conjugate base while a base is a molecule or ion which accepts the proton and produces a conjugate acid.
Thus, water H2O acts as a example of Bronsted-Lowry base while hydrochloric acid, HCl acts as an acid respectively as shown in the reaction below
HCl(aq) + H2O(aq) -> H3O+(aq) + Cl-(aq)
H2O acts as an base by accepting a proton donated by HCl, thus producing hydroxonium ion, H3O+ as a conjugate acid.
Thus, in the given reaction, H2O acts as a base