Which concept provides a ranking of relative clauses by the grammatical role they play, such as subject, direct object, and genitive?

• A. Accessibility hierarchy
• B. Frequency order
• C. Clause scale
• D. Morpheme ladder

Answer: (A)

The Accessibility Hierarchy for relative clauses ranks the possible relative clauses by the grammatical role of the head noun, from subject to direct object, indirect object, oblique, and genitive. This framework captures why some languages readily form subject and object relatives but rarely offer relatives for possessive (genitive) or other oblique roles—the higher a role is on the hierarchy, the more accessible it is to form a relative clause about it. The correct term names this established ranking, which is why it’s the best answer. Other terms like frequency order, clause scale, or morpheme ladder don’t describe this cross-linguistic pattern of relative-clause formation by syntactic role.