The correct answer is (C) Word derivations; the history of a particular word. Also, that field of linguistics that deals with the origin, formation, meaning, and inflexions of words and evolution of vocabulary.

Etymology comes from Old French ethimologie, Greek etumologia (etumos [true] + logos [word]).

Examples of use:

• The study of etymology should be part of any program of linguistics.
• She frequently mistook entomology for etymology.