题目内容：
根据以下材料，回答题Lookingbackonmychildhood,Iamconvincedthatnaturalistsarebornandnotmade.Althoughwewerebroughtupinthesameway,mybrothersandsisterssoonabandonedtheirpressed
flowersandinsects.Unlikethem,Ihadnoearformusicandlanguages.IwasnotanearlyreaderandIcouldnotdomentalarithmetic.
BeforeWorldWarIwespentoursummerholidaysinHungary.Ihaveonlythedimmemoryofthehousewelivedin,ofmyroomandmytoys.NordoIrecallclearlythelargefamilyofgrandparents,
aunts,unclesandcousinswhogatherednextdoor.ButIdohaveacrystal-clearmemoryofdogs,thefarmanimals,thelocalbirdsandaboveall,theinsects.
Iamanaturalist,notascientist.Ihaveastrongloveofthenaturalworld,andmyenthusiasmhasledmeintovariedinvestigations.Ilovediscussingmyfavoritetopicsandenjoyburningthe
midnightoil,readingaboutotherpeople'sobservationsanddiscoveries.Thensomethinghappensthatbringstheseobservationstogetherinmyconsciousmind.Suddenlyyoufancyyouseethe
answertotheriddle,becauseitallseemstofittogether.Thishasresultedinmypublishing300papersandbooks,whichsomemighthonorwiththetitleofscientificresearch.
Butcuriosity,akeeneye,agoodmemoryandenjoymentoftheanimalandplantworlddonotmakeascientist;oneoftheoutstandingandessentialqualitiesrequiredisself-discipline,aqualityIlack.Ascientistcanbemade.Anaturalistisborn.Ifyoucancombinethetwo,yougetthebestofbothworlds.
Accordingtotheauthor,abornnaturalistshouldfirstofallbe _______ A．fullofambition
B．self-disciplined
C．fullofenthusiasm
D．knowledgeable
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