Answer:
Winston thinks O'Brien is a member of the resistance, but discovers that he is an undercover government agent.
Step-by-step explanation:
This question is about the book "Nineteen eighty-four". In this book we are introduced to a totalitarian government that pursues individualism, freedom of expression and rationalism and any other type of political and social freedom.
Winston is the protagonist of the story and is part of a group that fights against the government. At a certain point he is introduced to O'brien who deceives him into thinking that he is an opponent of the government and allied with the resistance that Winston is part of, but he is an agent of the government and is there to torture all who oppose he.