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: NATIONAL GEOGRAPHIC 
Clue: The Vogalonga, an annual regatta seen here, takes place in this city
venice

Category: RIVERS 
Clue: The mouth of this 2315-mile-long river lies in the Mississippi River 17 miles above St. Louis
the missouri

Category: WOMEN IN SCIENCE 
Clue: In 1939 physicist Lise Meitner & her nephew Otto Frisch coined this term referring to the splitting of an atom's nucleus

nuclear fission