Which set of words are only adjectives?
Ridiculous, native, psychologise
Astronomy, sympathy, privacy
Nation, action, privacy
Chemical, mathematical, french
Chemical[Relating to or produced by means of chemistry], mathematical [elating to, or of the nature of mathematics], French [belonging to France]are all adjectives.
Ridiculous[adjective], native[noun], psychologise[verb];
Astronomy[noun], sympathy [noun], privacy[noun];
Nation[noun], action[noun], privacy[noun]
Therefore, Chemical, mathematical, french is the correct option.