(ii) When a pentavalent atom occupies the position of an atom in the crystal lattice of Si, four of its electrons form covalent bonds with four silicon neighbours, while the fifth remains bound to the parent atom. The energy required to set this electron free is about : (A) $0\cdot5\text{ eV}$ (B) $0\cdot1\text{ eV}$ (C) $0\cdot05\text{ eV}$ (D) $0\cdot01\text{ eV}$