Answer :
Answer:
A). Somebody.
Explanation:
Indefinite pronouns as the title suggest 'in-definite'(unspecified). These are illustrated as the pronouns that do not refer to a specific person, place, or object as it does not exactly mention the person or object it is referring or indicating to. For instance: anybody, somebody, someone, some, all, nothing, several, some, etc.
In the given question, the indefinite pronoun employed is 'somebody' as it doesn't indicate a particular person it is defining or referring to. 'He' knew that 'somebody' arrived late but do not know who. Thus, option A is the correct answer.
