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.
Position
Superior conductors have the authority to insist on intensified rehearsal work, even with a top orchestra. And they can't simply claim authority; they must earn it by gaining the orchestra’s respect for their artistic interpretations.
Evaluate
The question stem identifies this stimulus as a Position rather than argument/reasoning. So we don't have to force it into an argument framework if that feels unnatural. It doesn't seem like the 2nd sentence really supports the 1st one as much as it just elaborates on the details of the 1st one.
Goal
Since this doesn't have an argument structure, it's a little hard to anticipate what the author is assuming (we don't have an "If Premise, then Conclusion" type of reasoning move to scrutinize).
So we'll just have to look for some answer that feels implied by the stimulus.