Answer:
That character that seems unstable as she is pressured by both John and Abigail to testify is court is:
C. Mary Warren.
Step-by-step explanation:
In "The Crucible", a play by Arthur Miller, Mary Warren works as a maid for John Proctor, who is falsely accused of taking part in witchcraft rituals. Mary is quite a feeble character and gives in to pressure easily.
At first, as she sees innocent people being accused of crimes they did not commit, she feels bad. She agrees to testify against Abigail to save John Proctor. Later on, however, as she is pressured by Abigail, Mary becomes fearful of ending up being accused herself, so she turns against Proctor. She "confesses" to having been forced by him to practice witchcraft. As we can see, her character is unstable.