问题描述：
gmat语法问题
Thefactofsomefraternaltwinsresemblingeachothergreatlyandotherslookingquitedissimilarhighlightsaninterestingandoftenoverlookedfeatureoffraternal-twinpairs,namelytheyvaryconsiderablyonaspectrumofgeneticrelatedness.
A.Thefactofsomefraternaltwinsresemblingeachothergreatlyandotherslookingquitedissimilarhighlightsaninterestingandoftenoverlookedfeatureoffraternal-twinpairs,namelytheyvaryconsiderably
B.Thatsomefraternaltwinsresembleeachothergreatlywhileotherslookquitedissimilarhighlightsaninterestingandoftenoverlookedfeatureoffraternal-twinpairs,namelythattheyvaryconsiderably
C.Withsomefraternaltwinsresemblingeachothergreatlyandotherslookingquitedissimilar,ithighlightsaninterestingandoftenoverlookedfeatureoffraternal-twinpairs,namelyconsiderablevariation
D.Withsomefraternaltwinsresemblingeachothergreatlyandotherslookingquitedissimilar,itisafactthathighlightsaninterestingandoftenoverlookedfeatureoffraternal-twinpairs,namelyaconsiderablevariation
E.Becausesomefraternaltwinsresembleeachothergreatlyandotherslookquitedissimilar,thisfacthighlightsaninterestingandoftenoverlookedfeatureoffraternal-twinpairs,namelytheyvaryconsiderably
为啥是b?d错在哪里?