Visualization of B-cell traffic between the light and dark zones of the germinal center has shown that they migrate far less than had been predicted. This demonstrates that:
A. The traditional model of trafficking is inaccurate.
B. The rate of hypermutation and selection does not require extensive movement.
C. Only brief contacts by the B cells with helper T cells are needed.
D. Both B and C.
E. All of the above.
Answer: D