Which of the following is a biodegradable substance?

Options

A. detergent
B. pesticide
C. polythene
D. waste obtained from a biogas plant

Explanation

To determine which of the following options is a biodegradable substance, we need to understand what biodegradable means. A biodegradable substance is one that can decompose naturally in the environment over time. Let's analyze the options one by one:

1. **Detergent**: Detergents are made from synthetic chemicals and do not decompose easily. They are classified as non-biodegradable substances. Therefore, detergent is not the correct answer.

2. **Pesticides**: Pesticides are also chemically synthesized and are used in farming to eliminate pests. They do not decompose quickly and are considered non-biodegradable. Thus, pesticides are not the correct answer.

3. **Polythene**: Polythene, commonly used in plastic bags, is a non-biodegradable substance. It can remain in the environment for thousands of years without decomposing. Hence, polythene is not the correct answer.

4. **Waste obtained from a biogas plant**: This waste is derived from the decomposition of plant and animal matter. Since it is a natural product, it decomposes quickly and is considered biodegradable. Therefore, this option is the correct answer.

In conclusion, the biodegradable substance among the options provided is **the waste obtained from a biogas plant**.