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: SCIENCE FICTION 
Clue: A recent re-issue of this Sir Arthur Conan Doyle novel includes an introduction by Michael Crichton
the lost world

Category: MODERN LANGUAGES 
Clue: An estimated 100,000-plus people speak this language whose nouns have no gender & end with -o
esperanto

Category: ENTERTAINMENT 
Clue: It began in the early 1980s as Club des Talons Hauts, a stilt-walking troupe

cirque du soleil