premise: A bird sanctuary contains birds of at least two of the following six kinds—kingfishers, mynas, peacocks, robins, sparrows, and woodpeckers. No other kinds of birds are in the sanctuary. The following conditions must hold: Woodpeckers are not in the sanctuary if mynas are. Peacocks are not in the sanctuary if robins are. Either robins or woodpeckers, but not both, are in the sanctuary. Woodpeckers are in the sanctuary if kingfishers, sparrows, or both are in the sanctuary If there are no kingfishers in the sanctuary, then which one of the following must be true?
hypothesis: At least three kinds of birds are in the sanctuary.