DDT is banned because:

Options

A. it is highly toxic in human
B. long persistent in environment
C. kills insects like butterflies
D. used against mosquitoes

Answer

### Step-by-Step Solution:

1. **Identify the Full Form of DDT**:
- DDT stands for **Dichloro-Diphenyl-Trichloroethane**. This is important to understand what DDT is.

2. **Chemical Formula**:
- The chemical formula for DDT is **C14H9Cl5**. This indicates its composition and helps in understanding its chemical properties.

3. **Usage of DDT**:
- DDT is primarily used as a **synthetic insecticide**. It has been widely used to control insect populations, especially mosquitoes.

4. **Reasons for Banning DDT**:
- DDT is banned due to its **long persistence in the environment**. This means it does not break down easily and can remain in the ecosystem for a long time.
- It can **travel long distances** from the point of application, leading to widespread contamination.
- DDT **accumulates in the bodies of living organisms**, including humans, which can lead to harmful health effects.

5. **Health Effects**:
- Exposure to DDT can cause various health issues such as **vomiting, tremors, and seizures**. These effects highlight the toxicity of DDT in humans.

6. **Conclusion**:
- The primary reason for the ban on DDT is that it is **long persistent in the environment** and can accumulate in the body, leading to adverse health effects.

7. **Correct Answer**:
- Based on the analysis, the correct reason for banning DDT is that **it is long persistent in the environment**.