What is the nature of the mixture control in an engine with fuel injection?

In an engine with fuel injection, the mixture control is considered necessary because it plays a critical role in optimizing engine performance and efficiency. Fuel injection systems rely on precise control of the air-fuel mixture for combustion to occur effectively. This control ensures that the correct amount of fuel is injected into the combustion chamber relative to the amount of air available, which is vital for achieving optimal power output, fuel economy, and reduced emissions.

A well-regulated mixture control helps in adapting to varying operating conditions, such as load and temperature, allowing the engine to maintain performance and efficiency across a wide range of scenarios. Consequently, the necessity of mixture control highlights its importance in the overall functioning and reliability of modern fuel-injected engines.

In contrast, the other options detail different mechanisms or attributes that can be associated with fuel injection systems but do not encapsulate the fundamental importance that mixture control has for the operation of the engine.