Which type of ignition is characteristic of a compression ignition engine?

The characteristic type of ignition for a compression ignition engine is indeed the process of heat and pressure ignited. In a compression ignition engine, also known as a diesel engine, the fuel-air mixture is compressed to a very high pressure, which raises the temperature of the air significantly. When the fuel is injected into this highly compressed air, the elevated temperature ignites the fuel without the need for a spark plug, which is a defining feature of compression ignition. This process allows for a more efficient combustion cycle and is a fundamental principle behind the operation of diesel engines, distinguishing them from spark ignition engines that rely on an electrical spark to ignite the fuel-air mixture.

The other options do not accurately describe the ignition process in compression ignition engines. Electrical spark ignition refers to gas or petrol engines, chemical reaction ignition could imply combustion processes driven by chemical catalysts, and magical field ignited is not a recognized method in engine technology.