Answer: The pronoun "it" should be changed to "the song"
Explanation: The last option is the only one which solves the ambiguity of the pronoun "it," whose antecedent in this sentence was not clearly defined and could have been "the guitar" or "the song." All the other options lead to invalid sentences: "we" is always a subject, not an object in this sentence (so it can't be changed to "us"), replacing "he" with "they" would break coherence with "<em>his</em> guitar" and the possessive pronoun "his" would lose its function if changed to the reflexive pronoun "himself".
This is a great line and sequence from this play. If you haven't already seen the film version with Daniel Day-Lewis, please do so. Day-Lewis delivers the above line in such a way that it is the part that I remember the most.
At this point in the play, John Proctor has already admitted to the court that he committed adultery with Abigail Williams. In essence, he has intentionally hurt his reputation in the community. Many people looked up to Proctor as a good, strong, and moral man, but the adultery will taint that image.
The court asks John to sign his name and admit to witchcraft, and John refuses to let the court keep the paper that he signed. John is okay with his reputation being hurt because he was trying to save others, but he is not okay with his name (and his family's name) being tainted by...
