Exp) Option d is the correct answer.

Option I is incorrect: Not all UAVs are capable of vertical landing. Only UAVs designed with VTOL (Vertical Take-Off and Landing) capabilities can land vertically.

1. Multirotor UAVs (e.g., quadcopters, hexacopters) : These drones can take off and land vertically, because they generate lift directly from their rotors, making them suitable for operations in confined spaces
2. Fixed-Wing UAVs: Resembling traditional airplanes, these drones require runways or catapult systems for takeoff and landing. They cannot perform vertical landings unless specifically designed as hybrid VTOL (Vertical Take-Off and Landing) systems.
3. Hybrid VTOL UAVs: These combine features of both fixed-wing and rotary-wing designs, allowing for vertical takeoff and landing as well as efficient forward flight

So, not all UAVs have vertical landing capability.

Option II is incorrect: Hovering refers to maintaining a stationary position in the air without moving forward or backward. Automated hovering means the UAV can maintain its position without manual input. Again, only certain types of UAVs can do this.

1. Multirotor UAVs: These can hover easily due to their multiple rotors and precise thrust control. They often come with GPS and autopilot systems that allow automated hovering at a fixed altitude and position.
2. Fixed-Wing UAVs: These cannot hover because they depend on constant forward movement to generate lift. They behave like small airplanes and will stall if they try to stop moving forward.

Hence, not all types of UAVs can do automatic hovering.

Option III is incorrect: UAVs utilize various power sources depending on their design and intended use:

1. Battery-Powered (usually lithium-polymer or lithium-ion) UAVs: Common among small drones, batteries offer a clean and quiet power source but are limited in energy density.
2. Internal Combustion Engine (petrol/diesel) UAVs: Used in larger drones, these engines provide higher energy density, allowing for longer flight times.
3. Fuel Cell-Powered UAVs: These systems offer high energy efficiency and are used in specialized applications.
4. Hybrid Systems: Combining batteries with other power sources like fuel cells or combustion engines, these systems aim to balance endurance and performance.

Therefore, not all UAVs rely solely on batteries for power.

Source: https://www.auav.com.au/articles/drone-types/

https://www.shearwater.ai/post/6-energy-sources