题目内容：
根据短文，回答题。Greenspacefacilitiesarecontributingtoanimportantextenttothequalityoftheurbanenvironment．Fortunatelyitisnolongernecessarythateverylectureoreverybookaboutthissubjecthastostartwiththeproofofthisidea．Atpresentitisgenerallyaccepted，althoughmoreasaself-evidentstatementthanonthebaseofaclosely-reasonedscientificproof．Therecognitionoftheimportanceofgreenspaceintheurbanenvironmentisafirststepontherightway，thisdoesnotmean，however，thatsufficientdetailsareknownaboutthefunctionsofgreenspaceintownsandaboutthewayinwhichtheinhabitantsareusingthesespaces．AstothisrathercomplexsubjectIshall，withinthescopeofthislecture，enterintooneaspectonly，namelytherecreativefunctionofgreenspacefacilities．Thetheoreticalseparationofliving，working，trafficandrecreationwhichformanyyearshasbeenusedintownandcountryplanning，hasinmyopinionresultedindisproportionateattentionforformsofrecreationfarfrom，whereastherewasrelativelylittleattentionforimprovementofrecreativepossibilitiesinthedirectneighbourhoodofthehome．Wehavecometotheconclusionthatthisisnotright，becauseanimportantpartofthetimewhichwedonotpassinsleepingorworking，isusedforactivitiesatandaroundhome．Soitisobviousthatrecreationintheopenairhastobeginatthestreet-doorofthehouse．Theurbanenvironmenthastoofferasmanyrecreationactivitiesaspossible，andthedesignofthesehastobesuchthatmoreobligatoryactivitiescanalsohavearecreativeaspect．
Thevervbeststandardoflivingisnothingifitisnotpossibletotakeapleasantwalkinthedistrict，ifthechildrencannotbeallowedtoplayinthestreetsbecausetherisksoftrafficaretoogreat，ifduringshoppingyoucannowherefindaspotofenjoyingforamomenttheniceweather，inshort，ifyouonlyfeelyourselfathomeafterthestreet-doorofyourhouseisclosedafteryou．ACCOrdingtotheauthor，theimportanceofgreenspaceintheurbanenvironment__________． A．isstillunknown
B．isbeingcloselystudied
C．isusuallyneglected
D．hasbeenwidelyaccepted
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