The correct answer is: B. Only 2
Statement 1 is incorrect. Diesel engines do not use spark plugs to ignite the fuel-air mixture. Instead, the fuel-air mixture is compressed until it ignites spontaneously. This means that the octane rating of the fuel is not as important for diesel engines as it is for gasoline engines.
Statement 2 is correct. Gasoline engines use spark plugs to ignite the fuel-air mixture. If the fuel-air mixture is compressed too much, it can ignite before the spark plug fires. This is called “engine knocking” or “pinging”. Engine knocking can damage the engine, so it is important to use gasoline with a high enough octane rating to prevent it.
The octane rating of a fuel is a measure of its resistance to knocking. The higher the octane rating, the more resistant the fuel is to knocking. Gasoline engines with higher compression ratios require higher octane fuel to prevent knocking.