The correct answer is C. Batteries.
Submarines move under water by using batteries to power their electric motors. The batteries are charged by the submarine’s diesel engines when the submarine is on the surface. When the submarine is submerged, the diesel engines are turned off and the batteries provide the power to run the submarine’s motors.
Petrol and oxygen are not used to power submarines because they are flammable and could cause an explosion. Diesel engines are used to power submarines when they are on the surface, but they cannot be used when the submarine is submerged because they require air to operate. Steam is not used to power submarines because it is not a very efficient way to generate power.
Here is a brief explanation of each option:
- Option A: Petrol and oxygen are not used to power submarines because they are flammable and could cause an explosion.
- Option B: Diesel engines are used to power submarines when they are on the surface, but they cannot be used when the submarine is submerged because they require air to operate.
- Option C: Batteries are used to power submarines when they are submerged.
- Option D: Steam is not used to power submarines because it is not a very efficient way to generate power.