The correct option is B Common Noun
A common noun names a general person, place or thing, as the italicized word 'principal' is a common noun which refers to a person who's the head of a school, hence option B is correct. Abstract nouns denote a concept, an idea or state of being or any such non-physical entity, the 'principal' does not denote a concept or idea as the noun is a person, hence option A is incorrect. Collective nouns refer to a group of people or things, the 'principal' is a single person, and a group can't be made of only one person, hence option C is incorrect. Option D is incorrect because the noun 'principal' is a common noun, which is option B.