题目内容：
根据以下材料，回答题SanFranciscohasitscablecars.SeattlehasitsSpaceNeedle.And,Longviewhasitssquirrelbridge.Thebridge,whichhasattractedinternationalattention,isnowalocallandmark.
TheNuttyNarrowsBridgewasbuiltin1963byalocalbuilder,AmosPeters,togivesquirrelsawaytocrossthebusyroadwithoutgettingflattenedbypassingcars.
TheoriginalbridgewasbuiltoverOlympiaWayonthewestedgeofthelibrarygrounds.Beforethebridgewasbuilt,squirrelshadtoavoidtraffictoandfromtheParkPlazaofficebuildingwhere
officestaffputoutanuttyfeastforthesquirrels.Manytimes,PetersandotherswhoworkedinandnearParkPlazawitnessedsquirrelsbeingrunover.OnedayPetersfoundadeadsquirrelwith
anutstillinitsmouth,andthatday'scoffeebreakdiscussionturnedintosquirrelsafety.Thegroupofbusinessmencookedupthesquirrelbridgeideaandformedacommitteetoasktheblessing
oftheCityCouncil.TheCouncilapproved,andCouncilwomanBessLaRivierenamedthebridge"NuttyNarrows."
Afterarchitectsdesignedthebridge,AmosPetersandBillHutchstartedconstruction.Theybuiltthe60-footbridgefromaluminumandlengthsoffirehose.Itcost$1000.
Itdidn'ttakelongbeforereportsofsquirrelsusingthebridgestarted.Squirrelswereevenseenguidingtheiryoungandteachingthemtherop_.Thestorywaspickedupbythemedia,andNutty
Narrowsbecameknowninnewspapersallovertheworld.
In1983,after20yearsofuse,Peterstookdowntheworn-outbridge.Repairsweremadeandcrosspieceswerereplaced.ThefadedsignwasrepaintedandinJuly1983,hundredsofanimalloversattendedthecompletionceremonyofthenewbridge.
Petersdiedin1984,andaten-footwoodensquirrelsculpturewasplacednearthebridgein
memoryofitsbuilderandhisdevotiontotheproject.
Whatdoestheunderlinedphrase"teachingthemtheropes"probablymeansinthetext'?. A．Passingthemarope
B．Directingthemtostorefoodforwinter
C．Teachingthemalesson
D．Showingthemhowtousethebridge
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答案解析：