题目内容：
根据以下材料，回答题
DangersAwaitBabieswithAltitude
Womenwholiveintheworld'shighestcommunitiestendtogivebirthtounder-weightbabies,anewstudysuggests.Thesebabiesmaygrowintoadultswithahighriskofheartdiseaseandstrokes.
Researchhashintedthatnewbornsinmountaincommunitiesarelighterthanaverage.Butitwasn'tclearwhetherthisisduetoreducedoxygenlevelsathighaltitudeorbecausetheirmothersareunder-nourished--manypeoplewholiveathighaltitudesarerelativelypoorcomparedwiththoselivinglowerdown.
Tofindoutmore,DinoGiussaniandhisteamatCambridgeUniversitystudiedtherecordsof400birthsinBoliviaduring1976and1998.Thebabieswereborninbothrichandpoorareasoftwocities:LaPazandSantaCruz.LaPazisthehighestcityintheworld,at3.65kilometersabovesealevel,whileSantaCruzismuchlower,at0.44kilometers.
Sureenough,GiussanifoundthattheaveragebirthweightofbabiesinLaPazwassignificantlylowerthaninSantaCruz.Thiswastrueinbothhighandlow-incomefamilies.EvenbabiesborntopoorfamiliesinSantaCruzwereheavieronaveragethanbabiesborntowealthyfamiliesinloftyLaPaz."Wewereverysurprisedbythisresult,"saysGiussani.
Theresultssuggestthatbabiesbornathighaltitudearedeprivedofoxygenbeforebirth."Thismaytriggerthereleaseorsuppressionofhormonesthatregulategrowthoftheunbornchild,"saysGiussani.
Histeamalsofoundthathigh-altitudebabiestendedtohaverelativelylargerheadscomparedwiththeirbodies.Thisisprobablybecauseafetusstarvedofoxygenwillsendoxygenatedbloodtothebraininpreferencetorestofthebody.
Giussaniwantstofindoutifsuchbabieshaveahigherriskofdiseaseinlaterlife.PeopleborninLaPazmightbepronetohearttroubleinadulthood,forexample.Lowbirthweightisariskfactorforcoronary(冠状的)heartdisease.Andnewbornswithahighratioofheadsizetobodyweightareoftenpredisposedtohighbloodpressureandstrokesinlaterlife.
Whatdoesthenewstudydiscover? A．Babiesborntowealthyfamiliesareheaver.
B．Womenlivingathighaltitudetendtogivebirthtounder-weightbabies.
C．Newbornsincitiesarelighterthanaverage.
D．Low-altitudebabieshaveahighriskofheartdiseaseinlaterlife.
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