Which of the following contains a vague pronoun reference?

 - Steven felt better about collaborating on the research project after Rick talked with him about it.
 - After Rick talked with Steven about the research project, he felt better about collaborating on it.
The first answer choice contains a vague pronoun reference. The pronoun he could refer to Rick or Steven.
After Rick talked with Steven about the research project, he felt better about collaborating on it.
The second answer choice shows a possible correction for the vague pronoun reference. The text has been rewritten so that the meaning is clear.
Steven felt better about collaborating on the research project after Rick talked with him about it.