Which of the following contains a vague pronoun reference?

 - Molly looks almost identical to her twin sister Julia, but she has pierced ears.
 - Molly has pierced ears, but otherwise she looks almost identical to her twin sister Julia.
The first answer choice contains a vague pronoun reference. The pronoun she could refer to Molly or Julia.
Molly looks almost identical to her twin sister Julia, but she has pierced ears.
The second answer choice shows a possible correction for the vague pronoun reference. The text has been rewritten so that the meaning is clear.
Molly has pierced ears, but otherwise she looks almost identical to her twin sister Julia.