Fill in the blank (_) in the following sentence from the following choices.
Sentence: I poured cow's milk from the bottle into the cup until the _ was full.

Choice 1: I poured cow's milk from the bottle into the cup until the bottle was full.
Choice 2: I poured cow's milk from the bottle into the cup until the cup was full.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
2
2.