What does the host mean when he says that the acid has "donated a proton" to the water?

A.

When hydrochloric acid is dissolved in water, a proton disappears in the chemical reaction.

B.

When hydrochloric acid dissociates, a positive hydrogen atom is accepted by water to form H₃O+.

C.

When hydrochloric acid dissociates, a negative hydrogen atom is accepted by water to form H₃O-.