Which of the following contains a vague pronoun reference?
A. As Eva entered the harbor, her sailboat bumped into the old wooden pier; she was relieved that it didn't sustain any damage.
B. As Eva entered the harbor, her sailboat bumped into the old wooden pier; she was relieved that the boat didn't sustain any damage.
From the given choices, select the correct answer and reply with the letter of the chosen option.

A