Fill in the blank (_) in the following sentence from the following choices.
Sentence: Dennis was exhausted at the end of the day but Robert wasn't because _ had spent the day planting trees.

Choice 1: Dennis was exhausted at the end of the day but Robert wasn't because Dennis had spent the day planting trees.
Choice 2: Dennis was exhausted at the end of the day but Robert wasn't because Robert had spent the day planting trees.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
1
1.