One way in which the operation of an `npn` transistor differ from that of a `pnp` transistor is that
A. the emitter junction is reverse biased in `npn`
B. the emitter junction injects minority carriers into the base region of the `pnp`.
C. the emitter injects holes into the base of the `pnp` and electrons into the base region of `npn`
D. the emitter injects holes into the base of `npn`.
