Although vocal cords are lacking in cetaceans, phonation is undoubtedly centered in the larynx. The toothed whales or odontocetes (sperm whales and porpoises) are much more vociferous than the whalebone whales, or mysticetes. In this country observers have recorded only occasional sounds from two species of mystieetes (the humpback and right whale). A Russian cetologist reports hearing sounds from at least five species of whalebone whales but gives no details of the circumstances or descriptions of the sounds themselves. Although comparison of the sound-producing apparatus in the two whale groups cannot yet be made, it is interesting to note that the auditory centers of the brain are much more highly developed in the odontocetes than in the mystieetes, in fact, to a degree unsurpassed by any other mammalian group. According to the information given ______.
A．porpoises have vocal cords but right whales do not B．Russians report vocal cords in five species of whales C．there is a correlation between vocal cords and auditory areas of the brain D．whales do not have vocal cords