Legal Principle: Mere silence as to the facts likely to affect the willingness of a person to enter into a contract is not a fraud, unless the circumstances of the case are such that, on close examination it is found to be the duty of the person keeping silence to speak or unless his silence is, in itself, equivalent to speech.
Factual Situation: X sells by auction to Y, a horse which X knows to be of unsound state of mind. X says nothing to Y about the horse's unsound state of mind. Give the correct answer.