Mg and Fe are needed for plants in the

Options

A. energy transfer
B. synthesis of Chlorophyll pigment in the leaves
C. stomatal opening
D. translation of carbohydrates

Answer

To solve the question regarding the role of magnesium (Mg) and iron (Fe) in plants, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Nutrients**: Recognize that magnesium and iron are essential nutrients for plants. They are classified as micronutrients, which are required in smaller quantities compared to macronutrients.

2. **Understand Their Functions**:
- Magnesium is crucial for the formation of chlorophyll, the green pigment in plants that is essential for photosynthesis.
- Iron is also important for the synthesis of chlorophyll and other pigments.

3. **Analyze the Options**:
- **Option A: Energy transfer** - While magnesium plays a role in energy transfer as part of ATP, it is not the primary function of magnesium and iron in this context.
- **Option B: Synthesis of chlorophyll pigment in the leaves** - This option directly relates to the roles of both magnesium and iron.
- **Option C: Stomatal opening** - This process is primarily regulated by other factors and not directly by magnesium or iron.
- **Option D: Translation of carbohydrates** - This is more related to the metabolic processes of plants and does not directly involve magnesium or iron.

4. **Conclusion**: Based on the analysis, the most accurate answer is **Option B: Synthesis of chlorophyll pigment in the leaves**. Both magnesium and iron are essential for the synthesis of chlorophyll, which is vital for photosynthesis.

### Final Answer:
**B: Synthesis of chlorophyll pigment in the leaves.**