The correct answer is C. Boron.
A p-type semiconductor is a semiconductor in which the majority charge carriers are positive holes. It is created by doping an intrinsic semiconductor with a group III element. The group III element has one less valence electron than silicon, so it creates a hole in the valence band. This hole can then be used to conduct electricity.
Phosphorus, antimony, and germanium are all group V elements. They have five valence electrons, which is one more than silicon. When these elements are doped into silicon, they form an n-type semiconductor. In an n-type semiconductor, the majority charge carriers are electrons.
Boron is a group III element. It has three valence electrons, which is one less than silicon. When boron is doped into silicon, it forms a p-type semiconductor. In a p-type semiconductor, the majority charge carriers are holes.
Therefore, the impurity atoms with which silicon should be doped to make p-type semiconductors are boron.