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. Thispassagefocuseson__________. 查看材料
A.the difference between biological and clinical death
B.the process of dying
C.prolonging the period of clinical death
D.the nature of clinical death
正确答案是C