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.
--------
Question: Category: INSECTS 
Clue: This snout beetle reached Texas from Mexico around 1890 & spread into most cotton-growing areas of the U.S.

Answer: the boll weevil


Question: Category: RULERS 
Clue: In 770 this king of the Franks married Desiderata, daughter of the Lombard king Desiderius

Answer: charlemagne


Question: Category: ROBOTICS 
Clue: This type of vision allows robots to compare 2 images & thus to judge distances

Answer:
stereoscopic vision