The answer to the question is letter "B. informal". This is the level of diction which is conversational. This includes documents, personal letters, emails, and others that are aimed to converse and entertain. Further, this also sometimes includes "slang" language.
Answer: Singular Verbs
Explanation:
Subjects and verbs must AGREE with one another in number (singular or plural). Thus, if a subject is singular, its verb must also be singular; if a subject is plural, its verb must also be plural. Verbs REMOVE an s from the singular form.