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(B) The process of adding impurity atoms to a pure semiconductor is known as doping. Adding impurities increases the number of charge carriers (electr

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decreases

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(B) The process of adding impurity atoms to a pure semiconductor is known as doping. Adding impurities increases the number of charge carriers (electrons or holes) in the semiconductor. Since the conductivity $(\sigma)$ of a semiconductor is directly proportional to the number of charge carriers $(n)$, i.e., $\sigma = ne\mu$, where $e$ is the charge and $\mu$ is the mobility, an increase in the number of charge carriers leads to an increase in conductivity. Resistivity $(\rho)$ is the reciprocal of conductivity $(\rho = 1/\sigma)$. Therefore, as the conductivity increases due to doping, the resistivity of the semiconductor decreases.

When a small amount of impurity atoms are added to a semiconductor, then generally its resistivity:

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