题目内容：
Questionsarebasedonthefollowingpassage:
Peopleallovertheworldtodayarebeginningtohearandlearnmoreandmoreabouttheproblemofpollution.Pollutioniscausedeitherbyman'sreleaseofcompletelynewandoftenartificial(人造)substancesintotheenvironment,orbyreleasinggreatlyincreasedamountsofanaturalsubstance(物质),suchasoilfromoiltankersintothesea.
Whateveritsunderlyingreasons,thereisnodoubtthatmuchofthepollutioncausedcouldbecontrolledifonlycompanies,individualsandgovernmentswouldmakemoreefforts.Inthehomethereisanobviousneedtocontrollitterandwaste.Foodcomeswrappedupthreeorfourtimesinpackagesthatallhavetobedisposedof;drinksareincreasinglysoldinbottlesortinswhichcannotbereused.Thisnotonlycausesalitterproblem,butalsoisagreatwasteofresources,intermsofglass,metalandpaper.Advertisinghashelpedthisprocessbypersuadingmanyofusnotonlytobuythingweneitherwantnorneed,butalsotothrowawaymuchofwhatwedobuy.Pollutionandwastecombinetobeaproblemeveryonecanhelptosolvebycuttingoutunnecessarybuying,excessuseandcarelessdisposal(处理)oftheproductsweuseinourdailylives.
Themaincauseofpollutionis（ ）. A．thereleaseofartificialornaturalsubstancesintotheenvironment
B．theproductionofnewindustrialgoods
C．increasedamountsofanaturalsubstance
D．ourever-increasingpopulation
参考答案：
答案解析：