A persistent insecticide is

Options

A. Organophosphates
B. carbamates
C. Thiocarbamates
D. Chlorinated hydrocarbons.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks us to identify which of the given options is a persistent insecticide. Persistent insecticides are those that remain in the environment for a long time after application.

2. **Analyzing the Options**:
- **Organophosphates**: These are a class of insecticides that are not typically persistent. They break down relatively quickly in the environment.
- **Carbamates**: Similar to organophosphates, carbamates are not known for their persistence and tend to degrade faster.
- **Thiocarbamates**: These are also not classified as persistent insecticides. They are derived from carbamates and share similar characteristics regarding their environmental degradation.
- **Chlorinated Hydrocarbons**: These are synthetic chemicals used in insecticides that are known for their persistence. They can remain in the environment for extended periods and accumulate in the fatty tissues of animals, leading to bioaccumulation in the food chain.

3. **Identifying the Correct Answer**: After analyzing all the options, it is clear that chlorinated hydrocarbons are the persistent insecticides among the given choices.

4. **Conclusion**: The correct answer to the question "A persistent insecticide is" is **chlorinated hydrocarbons**.

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