[单选题]
An n-type semiconductolo 5p yx a8xzc;;i+hc:r isb*cn+u ylkaa:g )et *;zml+m 2 produced 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
