Which of the following contains a vague pronoun reference?

 - Lester bought a program for the opera without realizing that it was in Russian.
 - Lester bought a program for the opera without realizing that the program was in Russian.
The second answer choice contains a vague pronoun reference. The pronoun it could refer to the program or the opera.
The first answer choice shows a possible correction for the vague pronoun reference. It has been replaced with the program.
Lester bought a program for the opera without realizing that the program was in Russian.