The first pictures of a war were taken by ______.

A．to tell people how serious the damage caused by landslides is
B．to tell people that sending workers to stabilize mountainsides is a risky job
C．to introduce a product that can be used to stabilize mountainsides
D．to show people how to use a new robot

A．it will be faster and cheaper than manual labor
B．it can climb mountainsides, drill holes, insert bars and cement
C．it can collect data on the slope's stability
D．it can drill without a human being on board