根据以下材料,回答题 Peoplehavesmokedcigarettesforalongtimenow.ThetobaccowhichisusedtomakecigaretteswasfirstgrowninwhatisnowpartoftheUnitedStates.ChristopherColumbus,whodiscoveredAmerica,sawtheIndianssmoking.SoonthedriedleavesweretransportedtoEurope.Inthelate1800s,theTurksmadecigarettespopular. Cigarettesmokecontainsatleasttwoharmfulsubstances,tarandnicotine.Tar,whichformsasthetobaccoburns,damagesthelungsandthereforeaffectsbreathing.Nicotine,whichisfoundintheleaves,causesthehearttobeatfasterandincreasesthebreathingrate.Nicotineinlargecankillapersonbystoppingaperson′sbreathingmuscles.Smokersusuallytakeinsmallamountsthatthebodycanquicklybreakdown. Nicotinecanmakenewsmokersfeeldizzy(头晕)orsicktotheirstomachs.Theheartrateforyoungsmokersincreases2to3beatsperminute.Nicotinealsolowersskintemperatureandreducesbloodflowinthelegsandfeet.Itplaysanimportantroleinincreasingsmokers′riskofheartdiseaseandstroke. Smokingcigarettesisdangerous.Cigarettesmokingwasthecauseoflungcancerandseveralotherdeadlydiseases. Whatisthemainpurposeofthefirstparagraph查看材料
A.To tell us the bad effects caused bysmoking cigarettes. B.To introduce the history of smoking. C.To let us know what the cigarettes aremade from. D.To tell the readers that Columbus foundthe Indians smoking.正确答案B