Jim Henson Pictures has optioned the Susan Cooper sci-fi novel “The Dark is Rising,” which will be produced by Duncan Kenworthy, the company announced Tuesday. Execs expect the pic’s budget to be in the $20 million range.Kenworthy, the producer of “Four Weddings and a Funeral” and the NBC miniseries “Gulliver’s Travels,” will work from a script by Andrew Klavan, who is expected to complete a screenplay by year’s end. Eoghan Mahony will exec produce. “Dark is Rising,” published in 1973 and a regular on elementary school reading lists, is the story of an 11-year-old’s discovery that he is the last member of an immortal fellowship dedicated to protecting the world from the rising forces of Dark. The protagonist embarks on a mythical adventure that tests his courage and fortitude. “Duncan is the perfect producer because he can create the world of magic with detail,” said Stephanie Allain, Jim Henson Pictures’ prez of production. Allain added that the Cooper work “has been a favorite book” of Henson prexy and CEO Brian Henson and that the company had expended considerable effort to secure the rights.