Task: Question Answering
Input (English): Problem: the population of locusts in a certain swarm doubles every two hours. if 4 hours ago there were 1,000 locusts in the swarm, in approximately how many hours will the swarm population exceed 128,000 locusts ?
Options: a. 12, b. 8, c. 4, d. 10, e. 16
Output (English): d