What could happen if a few injector spray holes become plugged?

When a few injector spray holes become plugged, it can lead to multiple detrimental effects on engine performance, which explains why the correct choice is all of the provided options.

Firstly, if the spray holes are blocked, the fuel atomization will be compromised. Proper atomization is essential for efficient fuel combustion, ensuring that the fuel mixes thoroughly with air. As a result, poor fuel combustion occurs, which can manifest in incomplete burning of the fuel. This situation can lead to increased emissions and reduced power output from the engine.

Additionally, improper fuel delivery caused by plugged injectors may result in combustion knock under load. Combustion knock, also known as pre-ignition or detonation, can occur when there is an uneven distribution of fuel entering the combustion chambers. This unevenness may cause certain areas to ignite prematurely or inconsistently leading to a knocking sound and potential engine damage.

Finally, excessive surging at governed speed can happen because the engine may struggle to maintain a steady speed. Fluctuations in power output due to inadequate fuel delivery can lead to rapid increases and decreases in engine speed, which might be noticeable as surging.

Therefore, if injector spray holes become plugged, it indeed affects all aspects mentioned: combustibility, performance stability,