[单选题]
An n-type semiconductor is produ; hjv :z.m i-zckq 0zo4vzf jv*pqd*66cfi-tu c 4nn6 l)9n0nv l0jfd-red by
A. doping the host crystal with donor impurities.
B. doping the host crystal with accepter impurities.
C. pure crystals of germanium.
D. none of the given answers