You will be given a trivia clue, and the category it belongs to. You should answer with the best answer that belongs in the category and is described by the clue. For simplicity, answers should be in all lower cased letters.

Category: AUTHORS 
Clue: This "Oz" author was urged to write his stories by his mother-in-law, noted suffragette Matilda Gage
baum

Category: BIOLOGY 
Clue: Like mushrooms, molds belong to this group of organisms that lack chlorophyll
fungi

Category: COUNTRIES OF THE WORLD 
Clue: You'll find this country's major airports in Varna, Burgas & Sofia

bulgaria