Which of the following is not correct about plant intoduction ?

Options

A. They give us new crops
B. They give us new varieties
C. There is risk of entry of disease, etc. in into the country
D. Quarantine is not necessary

Answer

### Step-by-Step Solution:

1. **Understanding Plant Introduction**:
- Plant introduction refers to the process of bringing new plant species or varieties into a new area or country. This can involve the introduction of new crops or the importation of existing crops in different varieties.

2. **Analyzing the Options**:
- **Option A**: "They give us new crops."
- This statement is correct because introducing new plants can lead to the development of new crops in the region.
- **Option B**: "They give us new varieties."
- This statement is also correct as new varieties of existing crops can be introduced through plant introduction.
- **Option C**: "There is a risk of entry of disease into the country."
- This statement is correct because introducing new plants can bring along pests and diseases that may affect local flora and fauna.
- **Option D**: "Quarantine is not necessary."
- This statement is incorrect. Quarantine is a crucial process to prevent the introduction of diseases and pests when new plants are brought into a country.

3. **Identifying the Incorrect Statement**:
- Since options A, B, and C are correct statements about plant introduction, the statement that is not correct is option D: "Quarantine is not necessary."

4. **Conclusion**:
- The answer to the question "Which of the following is not correct about plant introduction?" is **Option D**: "Quarantine is not necessary."