请阅读Passage1，完成题： Modernscientistsdividetheprocessofdyingintotwostages--clinicalortemporarydeathandbiologicaldeath.Clinicaldeathoccurswhenthevitalorgans,suchastheheartorlungs,haveceasedtofunction,buthavenotsufferedpermanentdamage.Theorganismcanstillberevived. Biologicaldeathoccurswhenchangesintheorganismleadtothedisintegrationofvitalcellsandtissues.Deathisthenirreversibleandfinal. Scientistshavebeenseekingawaytoprolongtheperiodofclinicaldeathsothattheorganismcanberevivedbeforebiologicaldeathoccurs.Thebestmethoddevelopedsofarinvolvescoolingoftheorganism,combinedwithnarcoticsleep.Byslowingdownthebody'smetabolism,coolingdelaystheprocessesleadingtobiologicaldeath. Toillustratehowthisworks,scientistsperformedanexperimentonasix-year-oldfemalemonkeycalledKeta.ThescientistsputKetatosleepwithanarcotic.Thentheysurroundedherbodywithice-bagsandbegancheckingherbodytemperature.Whenithaddroppedto28degreesthescientistsbegandrainingbloodfromitsbody.Themonkey'sbloodpressuredecreasedandanhourlaterboththeheartandbreathingstopped;clinicaldeathsetin.FortwentyminutesKetaremainedinthisstate.Hertemperaturedroppedto22degrees.Atthispointthescientistspumpedbloodintoitsbodyinthedirectionoftheheartandstartedartificialbreathing.Aftertwominutesthemonkey'sheartbecameactiveoncemore.Afterfifteenminutes,spontaneousbreathingbegan,andafterfourhoursKetaopenedhereyesandliftedherhead.Aftersixhours,whenthescientiststriedtogiveherapenicillininjection,Ketaseizedthesyringeandranwithitaroundtheroom.Herbehaviordifferedlittlefromthatofahealthyanimal. Thebeststatementofthemainideaofthispassageisthat__________. 查看材料
A.scientists have found a way to prolong the period of clinical death
B.biological death occurs when vital organs have suffered permanent damage
C.modern scientists divide the process of dying into clinical and biological death
D.cooling delays the processes leading to biological death
正确答案是A