Which one of the following elements is not required by plants for their healthy normal growth?

Options

A. Calcium
B. Magnesium
C. Lead
D. Iron

Answer

To determine which element is not required by plants for their healthy normal growth, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Essential Elements**:
- Plants require certain elements for their growth, known as essential elements. There are 17 essential elements categorized into macronutrients and micronutrients.

2. **Identify Macronutrients and Micronutrients**:
- Macronutrients are needed in larger quantities and include elements like Calcium and Magnesium.
- Micronutrients are required in smaller amounts and include elements like Iron.

3. **Analyze the Options**:
- Look at the options provided:
- **Calcium**: This is a macronutrient and is essential for plant growth.
- **Magnesium**: This is also a macronutrient and is essential for plant growth.
- **Lead**: This is not classified as either a macronutrient or a micronutrient and is considered toxic to plants, making it non-essential.
- **Iron**: This is a micronutrient and is essential for plant growth.

4. **Conclusion**:
- Among the options, Lead is the only element that is not required by plants for their healthy normal growth. Therefore, the answer is Lead.

### Final Answer:
The element that is not required by plants for their healthy normal growth is **Lead** (Option 3).

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