The correct answer is B. flame.
When a substance burns, it undergoes a chemical reaction with oxygen in the air. This reaction releases heat and light, which we see as a flame. The substances that vaporize during burning are called fuels. Fuels are typically hydrocarbons, which are molecules that are made up of hydrogen and carbon atoms. When hydrocarbons burn, they react with oxygen to form carbon dioxide and water vapor. The heat released by this reaction is what causes the flame.
Brent crude is a type of oil that is found in the North Sea. It is a light, sweet oil, which means that it has a low sulfur content. Diesel is a type of fuel that is used in diesel engines. It is a heavier oil than gasoline, and it has a higher boiling point. Petroleum is a type of oil that is found in the ground. It is a mixture of hydrocarbons, and it can be refined into gasoline, diesel, and other fuels.
In conclusion, the substances which vaporise during burning give a flame.