题目内容：
根据以下材料回答题 Itwasnot"thecometofthecentury"expertspredicteditmightbe．However,Kohoutekhasprovidedabonanzaofscientificinformation．Itwasfirstspotted370millionmilesfromEarth,byanastronomerwhowassearchingtheskyforasteroids,andafterwhomthecometwasnamed．Scien-tistswhotrackedKohoutekthetenmonthsbeforeitpassedtheEarthpredictedthecometwouldbeabrilliantspectacle．ButKohoutekfellshortofthesepredictions,disappointingmillionsofamateurSkywatchers,whenitprovedtoopaletobeseenwiththeunaidedeye．Researcherswereveryhappynonethelesswiththenewinformationtheywereabletogleanfromtheirinvestigationofthecomet.
Perhapsthemostsignificantdiscoverywastheidentificationoftwoimportantchemicalcompounds--methylcyanideandhydrogencyanide--neverbeforeseenincomets,butfounditthefarrea-chesofinterstellarspace．Thisdiscoveryrevealednewcluesabouttheoriginofcomets．Mostastron-omersagreethatcometsareprimordialremnantsfromtheformationofthesolarsystem,butwhethertheywerebornbetweenJupiterandNeptuneormuchfartherouttowardinterstellarspacehasbeenthesubjectofmuchdebate．Ifcompoundsnomorecomplexthanammoniaandmethane,keycom-ponentsofJupiter,wereseenincomets,itwouldsuggestthatcometsformwithintheplanetaryor-bits．Butmorecomplexcompounds,suchasthemethylcyanidefoundinKohoutek,pointtoforma-tionfarbeyondtheplanets;therethedeepfreezeofspacehaskeptthemunchanged.
WhywasKohoutekreferredtoas"thecometofthecentury"? A．Itwasthoughttobeextremelyold.
B．ItpassestheEarthonceacentury.
C．Scientistspredicteditwouldbeverybright.
D．Scientistshavebeentrackingitforacentury.
参考答案：
答案解析：