题目内容：
根据以下材料，回答题Lifegetsnoisiereverydayandveryfewpeoplecanfreefromnoiseofsomesortoranother.Itdoesn'tmatterwhereyoulive--inthemiddleofamoderncity,orafarawayvillage--thechancesthatyofiwillbedisturbedbyjetaeroplanes,transistorradios,oilpoweredengines,etc.,arealmosteverywhere.Weseemtobegettingusedtonoise,too.Somepeoplefeelquitelonely
withoutback-groundmusicwhiletheyaxeworking.
Scientifictestshaveshownthattotalsilencecanbeveryfrighteningexperienceforhumanbeings.However,somepeopleenjoylisteningtopopmusicwhichisveryloud,andthiscandoharmtotheir
eardrums(耳鼓).Thenoiselevelinsomediscoisfarabovetheusualsafetylevelforheavy
industrialareas.
Onerecentreportaboutnoiseandconcentration(专心)suggestedthatalthoughalotofpeoplesaythatanynoisedisturbstheirconcentration,whatreallyaffectstheirabilitytoconcentrateisachangeinthelevelofnoise.Itgoesontosaythata
backgroundnoise,whichdoesn'tchangetoomuch(music,forexample)mayevenhelppeopletoconcentrate.
Fromthispassage,thepollutionofnoise A．doesn'tmattermuch
B．hasbecomeworseeverywhere
C．hasbecomebetterinbigcities
D．hasbecomebetterinviltages
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答案解析：