题目内容：
根据以下材料，回答题 EatingPotatoesGivesYourImmuneSystemaBoost
Eatingpotatoesisnotonlygoodforbowelhealth,butalsoforthewholeimmunesystem,especiallywhentheycomeintheformofapotatosaladoreatencold.Inastudyonananimalmodel,researchersinSpainfoundthatpigsfedlarge（51）ofrawpotatostarch(RPS)notonlyhadahealthierbowel,butalsodecreasedlevelsofwhitebloodcells,（52）asleucocytesandlymphocytesintheirblood.Whitebloodcellsareproducedasa（53）ofinflammationordisease,generallywhenthebodyischallenged.
Thegeneraldown-regulationofleucocytesobservedbytheSpanishresearcherssuggestsanoverallbeneficialeffect,agenerallymore（54）body.Thereductioninleukocytelevelswasabout15percent.Lowerlymphocytelevelsarealsoindicativeof（55）levelsofinflammation,buttheobservedreductioninbothlymphocytedensity（56）lymphocyteapoptosisissurprising.
In（57）wasthelongeststudyofitskind,pigswerefedRPSover14weeksto（58）theeffectofstarchonbowelhealth."Theuseofrawpotatostarchinthisexperimentis（59）tosimulatetheeffectsofadiethighinresistantstarch,"saidstudyleaderJoseFranciscoPerezattheUniversitatAutonomadeBarcelona,Spain.
Humansdonoteat（60）potatoes,buttheydoeatalotoffoodsthatcontainresistantstarch,suchascoldboiledpotatoes,legumes,grains,greenbananas,pastaandcereals.About10percentofthestarcheatenbyhumanisresistantstarch--starchthatisnot（61）inthesmallintestineandsoisshuntedintothelargeintestinewhereitferments.Starchconsumptionisthoughttoreducethe（62）oflargebowelcancerandmayalsohaveaneffectonirritablebowelsyndrome(IBS).
ImmunologyexpertLenaOman'steam（63）foundthattheoveralllymphocytelevelsdonotvaryforIBSpatients,butthatlymphocytesaretransferredfromtheperipheralbloodtothegut,whichsupportthehypothesisofIBSbeing（64）leastpartiallyallinflammatorydisorder.ShesaysthedecreaseinlymphocytesobservedbytheSpanishisthereforeinteresting,andadietofresistantstarchmaybeworth（65）inIBSpatients.OmaniscurrentlyattheDepartmentofInternalMedicine,GoteborgUniversity,Sweden.ThestudyispublishedintheJournalofChemistryandIndustry,themagazineoftheSCI.
回答(51)题 A．quantities
B．qualities
C．varieties
D．societies
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