阅读下列短文，从每题所给的A、B、C和D项中，选出最佳选项，
A
Lisawasrunninglate.Lisa，25，hadalottodoatwork，plusvisitorsontheway:herparentswerecominginforThanksgivingfromherhometown.Butasshehurrieddownthesubwaystairs，shestartedtofeeluncomfortablywarn.Bythetimeshegottotheplatform，Lisafeltweakandtired--maybeithadn’tbeenagoodideatogivebloodthenightbefore，shethought.Sherestedherselfagainstapostclosetothetr acks.
Severalyardsaway，Frank，43，andhisgirlfriend，Jennifer，foundaspotclosetowherethefrontofthetr ainwouldstop.Theyweredeepindiscussionaboutahousetheywerethinkingofbuying.
Butwhenheheardthescream，followedbysomeoneyelling，“Oh，myGod，shefellin!”Frankdidn’thesitate.Hejumpeddowntothetr acksandransome40feettowardthebodylyingontherails.“No!Notyou!”hisgirlfriendscreamedafterhim.
Shewasrighttobealarmed.BythetimeFrankreachedLisa，hecouldfeelthetr acksshakingandseethelightcoming.Thetr ainwasabout20secondsfromthestation.
Itwashardtolifther.Shewasjustout.Buthemanagedtoraiseherthefourfeettotheplatform.sothatbystanderscouldholdherbythegrinsanddragherawayfromtheedge.ThatwaswhereLisabrieflyregainedconsciousness，feltherselfbeingpulledalongtheground，andsawsomeoneelseholdingherpurse.
Lisathoughtshe’dbeenrobbed.Awomanheldherhandandamangavehisshirttohelpstopthebloodpouringfromherhead.Andshetr iedtotalkbutshecouldn’t，andthatwaswhensherealizedhowmuchpainshewasin.
Policeandfireofficialssoonarrived，andFranktoldthestorytoanofficer.Jennifersaidherboyfriendwascalmontheir40-minutetr ainridedowntown—justashehadbeensecondsaftertherescue，whichmadeherthinkaboutherreactionatthetime.“Isawthetr aincomingand1wasthinkinghewasgoingtodie，”sheexplained.
41.WhatwasthemostprobablecauseforLisa’sweakness?
A.Shehadrunalongway.
B.Shefelthotinthesubway.
C.Shehaddonea1otofwork.
D.Shehaddonatedbloodthenightbefore.
正确答案：D
