Fill in the blank (_) in the following sentence from the following choices.
Sentence: Making crafts was fun and easy for Aaron but not Robert because _ had attended art school.

Choice 1: Making crafts was fun and easy for Aaron but not Robert because Aaron had attended art school.
Choice 2: Making crafts was fun and easy for Aaron but not Robert because Robert had attended art school.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
1
2.