Which statement correctly identifies the three listed fuel injection system types?

• A. All three are types: Unit Injector, Electronic Unit Injectors, and Common Rail Type Electronic Control
• B. Only Unit Injectors are types
• C. Common Rail is not a type
• D. They require spark plugs

Answer: (A)

The three items are all recognized types of fuel injection systems. A Unit Injector is a self-contained unit that combines the pump and injector, used on many older diesel engines. Electronic Unit Injectors are the same concept but with electronic control of each injector for precise timing and quantity. Common Rail with electronic control is a different approach where high-pressure fuel is stored in a common rail and injected by electronically controlled injectors. Because each of these represents a distinct injection system design, all three are correctly identified as types. The other options misstate the range of system types and, in the diesel context, spark plugs aren’t part of these injection systems, which rely on compression ignition rather than spark ignition.