Task: Question Answering
Input (English): Researchers now believe that the decline of the Maya was caused chiefly by:
(A)a cataclysm of some kind, such as an earthquake, volcano, or tsunami. (B)ecological degradation resulting from slash-and-burn farming techniques. (C)endless wars between neighboring Mayan city-states. (D)practices of interbreeding that led to a steep rise in congenital disorders.
Output (English): B