Three students—Aryan, Bhavna, and Charan—are suspected of breaking a window. One of them always tells the truth, one always lies, and one alternates between truth and lies. They make the following statements:
• Aryan: Charan broke the window. I am a truth-teller.
• Bhavna: Aryan is lying. Charan did not break it.
• Charan: I didn't do it. Bhavna is the one who always lies.
Who actually broke the window?

Answer: D. Cannot be determined

Test each person as the truth-teller. If Aryan tells the truth, Charan broke the window; Bhavna's two statements are both false (liar) and Charan says one false, one true thing (alternator) - this works. If Bhavna tells the truth, Charan did not break it; Aryan's statements are both false (liar) and Charan's are true then false (alternator) - this also works. If Charan tells the truth, Bhavna is the liar, so "Charan did not break it" would be false, contradicting Charan - impossible. Two arrangements fit and they disagree about the culprit, so it cannot be determined.

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