Green chemistry means such reactions which

Options

A. produce colour during reactions
B. reduce the use and production of hazardous chemicals
C. are related to the depletion of ozone layer
D. study the reactions in plants

Explanation

**Step-by-Step Solution:**

1. **Understanding Green Chemistry:**
Green chemistry refers to the design of chemical processes and products that minimize the use and generation of hazardous substances. It aims to reduce pollution and enhance sustainability in chemical practices.

2. **Analyzing the Options:**
- **Option A:** Reduce color during reaction.
- This is not a primary focus of green chemistry.
- **Option B:** Reduce the use and production of hazardous chemicals.
- This aligns with the principles of green chemistry.
- **Option C:** Are related to depletion of ozone layer.
- While green chemistry may help address ozone depletion, this is not a direct definition.
- **Option D:** Study the reaction in plants.
- This is not a focus of green chemistry.

3. **Identifying the Correct Answer:**
The correct answer is **Option B:** "Reduce the use and production of hazardous chemicals." This option directly reflects the goals of green chemistry.

4. **Conclusion:**
Green chemistry focuses on minimizing hazardous substances in chemical processes, making Option B the most accurate representation of what green chemistry means.