Answer:
H₂O
Step-by-step explanation:
A Brønsted-Lowry base accepts protons. As seen in the equation, H₂O gains a proton to become H₃O⁺. It has gained one proton- a hydrogen atom.
C₂H₃O₂⁻ is a conjugate base.
H₃O⁺ is a conjugate acid.
HC₂H₃O₂ is an acid [or a Brønsted-Lowry acid].