Select the option that can be used as a one-word substitute for the highlighted group of words.
Johnson wrote a drama in which he discusses the study of chemistry in a medieval fashion.

Correct option is C

The one-word substitute for the highlighted group of words is (c) alchemy.
In this context, "alchemy" refers to the ancient pseudoscience of trying to transform base metals into noble metals and searching for the elixir of life, which often involved the study of chemistry in a mystical or medieval manner.
Meanings of other options:
 Rhetoric: The art of effective and persuasive speaking or writing.
 Lexicography: The practice of compiling and editing dictionaries.
 Anthropology: The scientific study of human societies, cultures, and behavior.