Running engine too hot will result in-

Answer: Option D

The correct answer is D: All are correct
Here's why:
When an engine runs too hot, several problems can occur:
* Pre-ignition: This happens when the air-fuel mixture ignites before the spark plug fires.
High engine temperatures can cause hot spots in the combustion chamber (like carbon deposits or glowing valves) to ignite the mixture prematurely.
* Detonation (also known as 'Knocking' or 'Pinging'): This is an uncontrolled explosion of the air-fuel mixture in the cylinder.
Instead of burning smoothly, the mixture detonates, creating shockwaves.
Excessive heat significantly increases the risk of detonation.
* Knocking: As mentioned above, Knocking is the same as detonation.
So, since pre-ignition and detonation are caused by an engine running too hot, all options are correct.