Task: Question Answering
Input (English): Under which circumstance would an adaptation be useful that allows tadpoles to go through a shortened period of metamorphosis?  
 (A) when tadpoles need to swim immediately (B) when there is a limited amount of water in their environment (C) when there is a decrease in the number of predators (D) when tadpoles need to blend in with their surroundings
Output (English): B