题目内容：
请根据以下内容回答1-5题PuttingPlantstoWork
Usingthepowerofthesunisnothingnew.Peoplehavehadsolar-poweredcalculatorsandbuildingswithsolarpanelsfordecades.Butplantsaretherealexperts:They'vebeenusingsunlightasanenergysourceforbillionsofyears.
Cellsinthegreenleavesofplantsworkliketinyfactoriestoconvertsunlight,carbondioxide,andwaterintosugarsandstarches,storedenergythattheplantscanuse.Thisconversionprocessiscalledphotosynthesis.Unfortunately,unlessyou'reaplant,it'sdifficultandexpensivetoconvertsunlightintostorableenergy.That'swhyscientistsaretakingacloserlookatexactlyhowplantsdoit.
Somescientistsaretryingtogetplants,orbiologicalcellsthatactlikeplants,toworkasminiaturephotosyntheticpowerstations.Forexample,MariaGhirardioftheNationalRenewableEnergyLaboratoryinGolden,Colo.,isworkingwithgreenalgae.She'stryingtotrickthemintoproducinghydrogeninsteadofsugarswhentheyperformphotosynthesis.Oncetheresearcherscangetthealgaeworkingefficiently,thehydrogenthattheyproducecouldbeusedtopowerfuelcellsincarsortogenerateelectricity.
Thealgaearegrowninnarrow-neckedglassbottlestoproducehydrogeninthelab.Duringphotosynthesis,plantsnormallymakesugarsorstarches.“Butundercertainconditions,alotofalgaeareabletousethesunlightenergynottostorestarch,buttomakehydrogen.”Ghirardisays.Forexample,algaewillproducehydrogeninanairfreeenvironment.It'stheoxygenintheairthatpreventsalgaefrommakinghydrogenmostofthetime.Workinginanairfreeenvironment,however,isdifficult.It'snotapracticalwaytoproducecheapenergy.ButGhirardiandhercolleagueshavediscoveredthatbyremovingachemicalcalledsulfatefromtheenvironmentthatthealgaegrowin,theywillmakehydrogeninsteadofsugars,evenwhenairispresent.
Unfortunately,removingthesulfatealsomakesthealgae'scellsworkveryslowly,andnotmuchhydrogenisproduced.Still,theresearchersseethisasafirststepintheirgoaltoproducehydrogenefficientlyfromalgae.Withmorework,theymaybeabletospeedthecells'activityandproducelargerquantitiesofhydrogen.
Theresearchershopethatalgaewillonedaybeaneasy-to-usefuelsource.Theorganismsarecheaptogetandtofeed,Ghirardisays,andtheycangrowalmostanywhere:“Youcangrowtheminareactor,inapond.Youcangrowthemintheocean.There'salotofflexibilityinhowyoucanusetheseorganisms.”
WhatdoesthewriterSayaboutplantsconcerningsolarenergy?_______
A Plantsaretherealexpertsinproducingsolarenergy.
B Plantshavebeenusedtoproducesolarenergy.
C Plantshavebeenusingsolarenergyforbillionsofyears.
D Plantshavebeenasourceofsolarenergy.
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