With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements: [Defence]

I. All types of UAVs can do vertical landing.
II. All types of UAVs can do automated hovering.
III. All types of UAVs can use battery only as a source of power supply.

The correct option is None.

Let us analyze each statement step-by-step to understand why none of them are correct:

Statement I: "All types of UAVs can do vertical landing."
This statement is incorrect. While multirotor UAVs (like quadcopters) and Hybrid VTOL (Vertical Take-Off and Landing) UAVs can land vertically, fixed-wing UAVs (which look like traditional airplanes) cannot. Fixed-wing UAVs require a runway, a catapult launcher, or a parachute/net recovery system for landing.

Statement II: "All types of UAVs can do automated hovering."
This statement is incorrect. Hovering refers to remaining suspended in one place in the air. Multirotor UAVs excel at hovering, but conventional fixed-wing UAVs cannot hover because they must maintain forward motion to generate lift over their wings. If a conventional fixed-wing UAV stops moving forward, it will stall and fall.

Statement III: "All types of UAVs can use battery only as a source of power supply."
This statement is incorrect. While many small consumer drones run solely on lithium-polymer (LiPo) batteries, larger, long-endurance, or military UAVs (such as the MQ-9 Reaper or Global Hawk) use internal combustion engines or turboprops powered by liquid aviation fuels (like gasoline, heavy fuel, or jet fuel). Some advanced research UAVs also use hydrogen fuel cells or solar cells.

Since all three statements are incorrect, the correct option is indeed None.