55. Flagella are the major motility apparatus of bacteria. Which of the following descriptions ofbacterial flagella is correct? (A) Flagella in Gram-negative bacteria typically contain a multiple-ring structure. These rings, from thc inside of the cell to the outside, are the L ring, P ring, M/S ring, and C ring. (B) ATP is the direct energy source of bacterial flagella rotation. (C) The flagella filament is composed primarily of flagellin subunits and is assembled in cytoplasm. (D) The flagellar rotor could self-assemble in a spontaneous process. (E) Reversal of flagella rotation primarily concerns conformation change in the filament.