题目内容：
根据以下材料，回答题Electronicbookscouldrevolutionizereading,butpeopleoughttoconsidertheirfar-reaching."Thee-bookpromisestowreakaslowhavoconlifeasweknowit."JasonOhler,professoroftechnologyassessment,UniversityofAlaskaSoutheastinJuneau,warnedtheWorldFutureSociety,Bethesda,
Md.Hisassessmentweighedtheprosandconsofe-booktechnology'simpactonsocialrelationships,theenvironment,theeconomy,etc.Beforeyoucurlupwithane-book,considerthedisadvantages.
Theyincreaseeyestrainduetopoorscreenresolution,replacearelativelycheapcommoditywithamoreexpensiveone,anddisplaceworkersinprintbookproductionandtraditionalpublishing.E-booksmakeiteasytosharedata,therebythreateningcopyrightagreementsandreducingcompensationofauthors,aswellascreatingnonbiodegradabletrash.Ontheotherhand,e-bookssavepaperandtrees,reducetheburdenofthecarryingandstoringofprintedbooks,promoteself-sufficiencyinlearning,andmakereadingacollaborativeexperienceonline.Theyalsocreatenewjobsforwritersandartistsandencourageself-publishing.Infinalanalysis,Ohlerpointsout,e-booksshouldgainsociety'sapprovalifafewconditionsaremet:makethembiodegradableandrecyclable,solvetheproblemofeyefatigue,besurethe"have-nots"getthetechnology,andsupporte-booktraininginschoolsandbusiness.
Whatistheauthor'spurposeofwritingthepassage? A．Drawpeople'sattentiontothedisadvantagesofe-books.
B．Callonpeopletorejecte-books.
C．Criticizeschoolsandbusinessthatdon'tprovidee-books.
D．Encouragepeopletousee-books.
参考答案：
答案解析：