The author refers to "smokers" in the third paragraph most probably in order to A. show how thermal shock can provide food for some vent faunas by stunning small animals B. prove that the habitat of most deep-sea animals is limited to warm-water vents C. explain how bacteria carry out chemosynthesis D. demonstrate how advection compensates for the lack of food sources on the seafloor E. present evidence that bacterial chemosynthesis may be an inadequate source of food for some vent faunas