The correct answer is: D. Batteries.
Submarines use batteries for under water movement because they are quiet and efficient. Batteries are also reliable and can be stored for long periods of time without losing power.
Steam accumulators are not used in submarines because they are noisy and inefficient. Air motors are not used in submarines because they are not powerful enough to move a submarine through water. Diesel engines are used in submarines for surface movement, but they are not powerful enough to move a submarine through water when the submarine is submerged.
Here is a more detailed explanation of each option:
- Steam accumulators: Steam accumulators are devices that store steam under pressure. The steam can then be used to power a turbine, which can generate electricity or drive a propeller. Steam accumulators are noisy and inefficient, and they require a lot of maintenance.
- Air motors: Air motors are motors that are powered by compressed air. Air motors are not powerful enough to move a submarine through water.
- Diesel engines: Diesel engines are internal combustion engines that are powered by diesel fuel. Diesel engines are powerful and efficient, but they require a lot of oxygen to operate. When a submarine is submerged, it cannot take in enough oxygen to operate a diesel engine.
- Batteries: Batteries are devices that store electrical energy. Batteries can be used to power electric motors, which can drive a propeller. Batteries are quiet and efficient, and they do not require oxygen to operate.