This is the initial stage of oil that never developed completely into crude and is typical of oil shales. There are three types of these.

This is the initial stage of oil that never developed completely into crude and is typical of oil shales. There are three types of these.

• A. Bitumen
• B. Tar
• C. Asphalt
• D. Kerogen

Answer: (D)

Kerogen is the solid, insoluble organic material preserved in sedimentary rocks that serves as the starting point for hydrocarbon generation. In oil shales, you find kerogen that hasn’t yet cracked into crude oil, so it represents the early stage before maturation. With burial and heating over time, kerogen breaks down to produce liquids or gases, depending on its type. The three kerogen types reflect different original materials: Type I comes from algal-rich matter and is very oil-prone; Type II from marine plankton and also oil-prone; Type III from terrestrial plants and is more gas-prone. This is why kerogen fits the description in the question as the initial stage of oil generation, with three distinct types.

Kerogen is the solid, insoluble organic material preserved in sedimentary rocks that serves as the starting point for hydrocarbon generation. In oil shales, you find kerogen that hasn’t yet cracked into crude oil, so it represents the early stage before maturation. With burial and heating over time, kerogen breaks down to produce liquids or gases, depending on its type. The three kerogen types reflect different original materials: Type I comes from algal-rich matter and is very oil-prone; Type II from marine plankton and also oil-prone; Type III from terrestrial plants and is more gas-prone. This is why kerogen fits the description in the question as the initial stage of oil generation, with three distinct types.