Which of the following contains a vague pronoun reference?

 - The Doyles' car has a dent in the bumper, but otherwise their car looks just like the Shens'.
 - The Doyles' car looks just like the Shens', but theirs has a dent in the bumper.
The second answer choice contains a vague pronoun reference. The pronoun theirs could refer to the Doyles' or the Shens'.
The Doyles' car looks just like the Shens', but theirs has a dent in the bumper.
The first answer choice shows a possible correction for the vague pronoun reference. The text has been rewritten so that the meaning is clear.
The Doyles' car has a dent in the bumper, but otherwise their car looks just like the Shens'.