Bitumen, also known as asphalt, is a black, viscous, and sticky substance that is commonly used in road construction and waterproofing applications. It is obtained from petroleum products, making option 'C' the correct answer.

Here is a detailed explanation of why bitumen is obtained from petroleum products:

1. Formation of Petroleum:
- Petroleum is a naturally occurring fossil fuel that is formed over millions of years from the remains of plants and animals.
- These organic materials undergo decomposition and are subjected to high temperature and pressure deep within the Earth's crust, leading to the formation of crude oil or petroleum.

2. Composition of Petroleum:
- Petroleum is a complex mixture of hydrocarbons, which are organic compounds consisting of hydrogen and carbon atoms.
- It also contains small amounts of sulfur, nitrogen, oxygen, and trace elements.

3. Distillation of Crude Oil:
- Crude oil is a mixture of different hydrocarbons with varying boiling points.
- It is processed through a refining technique called fractional distillation, which separates the various components based on their boiling points.
- Bitumen is one of the heaviest components and has a higher boiling point than other petroleum products. It is obtained during the later stages of the distillation process.

4. Bitumen Production:
- Once the crude oil is distilled, bitumen is separated from the other components using further processing techniques such as vacuum distillation or solvent extraction.
- The resulting bitumen is a thick, sticky, and highly viscous liquid or semi-solid material.

5. Applications of Bitumen:
- Bitumen is widely used in road construction as it provides excellent binding properties, durability, and resistance to weathering.
- It is also used in the manufacturing of roofing materials, waterproofing membranes, adhesives, and sealants.

In conclusion, bitumen is obtained from petroleum products, specifically during the refining process of crude oil. It is a valuable material with various applications in construction and waterproofing industries.