请教一道GMAT逻辑题，真心琢磨不明白呀。.....
Frobisher,a
sixteenth-centuryEnglishexplorer,hadsoilsamplesfromCanada'sKodlunarn
Islandexaminedforgoldcontent.Becausehighgoldcontentwasreported,
ElizabethIfundedtwominingexpeditions.Neitherexpeditionfoundanygold
there.Modernanalysisoftheisland'ssoilindicatesaverylowgoldcontent.Thus
themethodsusedtodeterminethegoldcontentofFrobisher‘ssamplesmusthave
beeninaccurate.
Whichofthe
followingisanassumptiononwhichtheargumentdepends?
A.ThegoldcontentofthesoilonKodlunarnIslandismuch
lowertodaythanitwasinthesixteenthcentury.
B.ThetwominingexpeditionsfundedbyIdidnotminethe
samepartofKodlunarnIsland.
C.Themethodsusedtoassessgoldcontentofthesoil
samplesprovidedbyFrobisherweredifferentfromthosegenerallyusedinthe
sixteenthcentury.
D.Frobisherdidnothavesoilsamplesfromanyother
Canadianislandexaminedforgoldcontent.
E.Goldwasnotaddedtothesamplescollected
byFrobisherbeforethesampleswereexamined.
这道以答案是E，那为什么B不对呢？而且为什么选E，觉得E有点不合理
.