题目内容：
根据以下材料，回答题Socialchangeismorelikelytooccurinsocietieswherethereisamixtureofdifferentkindsofpeoplethaninsocietieswherepeoplearesimilarinmanyways.Thesimplereasonforthisisthatthere
aremoredifferentwaysoflookingatthingspresentinthefirstkindofsociety.Therearemoreideas,moredisagreementsininterest,andmoregroupsandorganizationswithdifferentbeliefs.
Inaddition,thereisusuallyagreaterworldlyinterestandgreatertoleranceinmixedsocieties.Allthesefactorstendtopromotesocialchangebyopeningmoreareasoflifetodecision.Inasociety
wherepeoplearequitesimilarinmanyways,therearefeweroccasionsforpeopletoseetheneedortheopportunityforchangebecauseeverythingseemstobethesame.Andalthoughconditions
maynotbesatisfactory,theyareatleastcustomaryandundisputed.Withinasociety,
socialchangesisalsolikelytooccurmorefrequentlyandmorereadilyinthematerialaspectsoftheculturethaninthenon-material,forexample,intechnologyratherthaninvalues;inwhathasbeenlearnedlaterinliferatherthanwhatwaslearnedearly;inthelessbasicandlessemotionalaspectsofsociety
thanintheiropposites;inthesimpleelementsratherthaninthecomplexones;informratherthaninsubstance;andinelementsthatareacceptabletothecultureratherthaninstrangeelements.
Furthermore,socialchangeiseasierifitisgradual.Forexample,itcomesmorereadilyinhumanrelationsonacontinuousscaleratherthanonewithsharpdifference.Thisisonereason
whychangehasnotcomemorequicklytoBlackAmericansascomparedtootherAmericanminori-ties,becauseofthesharpdifferenceinappearancebetweenthemandtheirwhitecounterparts.
Thepassageismainlydiscussing A．certainfactorsthatdeterminetheeasewithwhichsocialchangesoccur
B．certainfactorsthatpromotesocialchange
C．thenecessityofsocialchange
D．twodifferentsocieties
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答案解析：