问题：
[单选题] Text 3 Drones,originally developed for military purposes,weren't approved for commercial use in the United States until 2013.When that happened,it was immediately clear that they could be hugely usefu
A、It is under proper supervision.
B、It has multiple purposes.
C、It is opposed by people.
D、It has no security problem.
参考答案：
B、It has multiple purposes.
● 参考解析
