What are the author’s qualifications to write on the topic? can you guys ! ! explain this question

Iwould say a but i don’t know what words are underlined

Allusion and illusion. an allusion is an indirect reference, whereas an illusion is something that is unreal or incorrect. each of the nouns has a related verb form: allude “to refer indirectly to,” and illude (not a very common word), which may mean “to delude or deceive” or “to subject to an illusion.”