3. How does the author develop his central idea over the course of the article? A by explaining what a drone is, how it is built, and how it was historically developed by the military B by noting the ways in which a drone can be adapted for a variety of uses, such as surveying animals and protecting wildlife C by advocating for the non-military use of drones, so that they can only be used by commercial companies and scientists D by arguing for a more frequent use of drones as a means of general surveillance and spying