jEAn wAgnEr’s most EnDuring ContriBution to thE stuDy oFAFro-AmEriCAn poEtry is his insistEnCE thAt it ______ in rEligious, As wEll As worlDly, FrAmE oF rEFErEnCE.
A、is to BE AnAlyzEDB、hAs BEEn AnAlyzED
C、BE AnAlyzED
D、shoulD hAvE BEEn AnAlyzED