The correct answers are Who betrayed you during the island challenge? and Who did you betray during the island challenge?

Both of these are correct, but they ask very different things!

• Subject Question: "Who betrayed you?" (We don't know the subject. No auxiliary "did" is needed when who is the subject doing the action.)

• Object Question: "Who did you betray?" (You are the subject, so we need the auxiliary "did" before the subject.)

• "Who did betrayed you?" is incorrect because we don't use "did" with a past tense verb ("betrayed").

• "Who you betrayed?" is missing the auxiliary "did."