17. It is the mark of a superior conductor that he or she has the authority to insist, even with a top orchestra, that rehearsal work must be intensified. This authority cannot simply be claimed, the conductor must earn it by winning the orchestra's respect for the artistic interpretations he or she is currently pursuing.
In taking the position outlined, the author presupposes which one of the following?
(A) Superior conductors devise different interpretations of composition for each orchestra with which they perform it.
(B) Superior conductors are perfectionists who are never satisfied with any performance even by a top orchestra.
(C) Top orchestras are always ready to put in additional work on rehearsals if the conductor considers additional rehearsing necessary.
(D) Top orchestras can appreciate the merits of an interpretation even before they have brought it to full realization.
(E) Even top orchestras are not always led by superior conductors.
It is the mark of a superior conductor that he or she has the authority to insist, even with a top orchestra, that rehearsal work must be intensified.这个句子没看懂,it is是引导强调句吧,但是在后面做什么成分呀,请指教