An ideal fuel should have A. high calorific value B. low ignition value C. regulated and controlled D. All of the above

The correct answer is D. All of the above.

An ideal fuel should have the following properties:

• High calorific value. This means that the fuel should release a lot of energy when it is burned.
• Low ignition value. This means that the fuel should be difficult to ignite, so that it is not easily set on fire by accident.
• Regulated and controlled. This means that the fuel should be easy to control and regulate, so that it can be burned safely and efficiently.

A fuel with a high calorific value will release more energy when it is burned, which will provide more power. A fuel with a low ignition value will be less likely to ignite accidentally, which will make it safer to use. A fuel that is regulated and controlled will be easier to use and manage, which will make it more efficient.

All of these properties are important for an ideal fuel. A fuel that does not have all of these properties is not ideal.