Question

which of the following contains a vague pronoun reference?
jane asked lucy to make a flourless chocolate cake for their book club meeting because she has a gluten allergy.
because lucy has a gluten allergy, jane asked her to make a flourless chocolate cake for their book club meeting.

Explanation:

In the first sentence "Jane asked Lucy to make a flourless chocolate cake for their book club meeting because she has a gluten allergy", the pronoun "she" is vague as it's unclear if it refers to Jane or Lucy. In the second sentence, "her" clearly refers to Lucy (since it's stated Lucy has the allergy), so the first sentence has a vague pronoun reference.

Answer:

Jane asked Lucy to make a flourless chocolate cake for their book club meeting because she has a gluten allergy.