Which of the following contains a vague pronoun reference?

 - Jim plans to travel around Europe with his brother after he graduates.
 - After Jim graduates, he plans to travel around Europe with his brother.
The second answer choice contains a vague pronoun reference. The pronoun he could refer to Jim or his brother.
Jim plans to travel around Europe with his brother after he graduates.
The first answer choice shows a possible correction for the vague pronoun reference. The text has been rewritten so that the meaning is clear.
After Jim graduates, he plans to travel around Europe with his brother.