Fill in the blank (_) in the following sentence from the following choices.
Sentence: After her lips swelled up, Brian gave all the lip gloss to Christopher since _ was insensitive to it.

Choice 1: After her lips swelled up, Brian gave all the lip gloss to Christopher since Brian was insensitive to it.
Choice 2: After her lips swelled up, Brian gave all the lip gloss to Christopher since Christopher was insensitive to it.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
2
2.