277. Which of the combustion chambers shown in the illustration is referred to as an «energy cell» used in some small diesel engines

Choice A is correct; it depicts a small, separate precombustion chamber (energy cell) connected to the main cylinder via narrow passages, which defines an energy-cell diesel combustion system. This system utilizes a small auxiliary chamber in the cylinder head connected to the main cylinder by restricted passages, where fuel is injected and combustion gases are forced into the main chamber, creating turbulence and promoting mixing. This design, used in some small and medium-speed engines, improves starting, reduces knock, and simplifies fuel injection equipment by featuring a distinct cell volume in the head rather than a piston recess.