Fill in the blank (_) in the following sentence from the following choices.
Sentence: The librarian charged William a fine but not Steven because _ returned the book late.

Choice 1: The librarian charged William a fine but not Steven because William returned the book late.
Choice 2: The librarian charged William a fine but not Steven because Steven returned the book late.
Which of the choices is correct? Respond with only "1" or "2" and no additional text.
1
2.