Fill in the blank (_) in the following sentence from the following choices.
Sentence: The car passed the motorcycle on the highway because the _ was driving very slowly.

Choice 1: The car passed the motorcycle on the highway because the car was driving very slowly.
Choice 2: The car passed the motorcycle on the highway because the motorcycle was driving very slowly.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
2
2. The car passed the motorcycle on the highway because the motorcycle was driving very slowly.