Task: Question Answering
Input (English): Problem: a crow leaves its nest, and flies back and forth from its nest to a nearby ditch to gather worms. the distance between the nest and the ditch is 250 meters. in one and a half hours, the crow manages to bring worms to its nest 15 times. what is the speed of the crow in kilometers per hour ?
Options: a. 1, b. 3, c. 4, d. 5, e. 6
Output (English): d