Which of the following contains a vague pronoun reference?

 - At lunchtime, Brian can often be found reading at his favorite café, where they provide unlimited coffee refills.
 - At lunchtime, Brian can often be found reading at his favorite café, where the servers provide unlimited coffee refills.
The second answer choice contains a vague pronoun reference. The pronoun they is used without its antecedent.
The first answer choice shows a possible correction for the vague pronoun reference. They has been replaced with the servers.
At lunchtime, Brian can often be found reading at his favorite café, where the servers provide unlimited coffee refills.