Correct option is C
When Si is doped with phosphorus, an n-type semiconductor is formed.
Explanation:
n-type semiconductor: In an n-type semiconductor, the majority charge carriers are electrons.
Doping with phosphorus: Phosphorus is a pentavalent element, meaning it has five valence electrons. When added to silicon (a tetravalent element), the extra electron from phosphorus becomes free to move within the semiconductor lattice, creating an excess of electrons and forming an n-type semiconductor.
