🔍 Key Concepts

• Difference between diesel and gasoline (spark-ignition) engines • How air and fuel enter and are handled in a diesel cylinder • Role of compression and temperature in starting combustion

💭 Think About

• Ask yourself: Does a basic diesel engine normally use spark plugs or a distributor like a gasoline car engine? • What happens to the temperature of air when it is highly compressed in a cylinder? How does that affect injected fuel? • Which option describes something that occurs naturally from the engine cycle, not from an added electrical device?

✅ Before You Answer

• Verify which options mention electrical spark/discharge devices and recall if standard marine diesels use them. • Identify which choice involves compression of air and the resulting rise in temperature. • Check that the chosen option matches how fuel actually starts burning right after it is injected into very hot, compressed air.