The passage suggests that anyone attempting to evaluate Mendelssohn's career must confront which of the following dichotomies? A. The tension between Mendelssohn's career as a composer and his career as a pianist and conductor B. The contrast between Mendelssohn's popularity and that of Schumann and Brahms C. The discrepancy between Mendelssohn's popularity and his standing among critics D. The inconsistency between Mendelssohn's reputation during his lifetime and his reputation since his death E. The gap between Mendelssohn's prodigious musical beginnings and his decline in later years.