Which one of the following is not an essential mineral element for plants while the remaining three are?

Options

A. Cadmium
B. Phosphorus
C. Iron
D. Manganese

Answer

To determine which of the given options is not an essential mineral element for plants, we can follow these steps:

### Step 1: Understand Essential Mineral Elements
Essential mineral elements are those that are necessary for plant growth and development. They can be categorized into two groups:
- **Macronutrients**: Required in larger quantities (e.g., Calcium, Phosphorus, Potassium, Oxygen, Hydrogen, Carbon, Magnesium).
- **Micronutrients**: Required in smaller quantities (e.g., Zinc, Iron, Boron, Nickel).

### Step 2: Analyze the Options
The options provided are:
1. Cadmium
2. Phosphorus
3. Iron
4. Manganese

### Step 3: Identify Each Element's Role
- **Cadmium**: This is not an essential mineral element for plants. In fact, it is toxic to plants in high concentrations.
- **Phosphorus**: This is a macronutrient essential for energy transfer and photosynthesis.
- **Iron**: This is a micronutrient essential for chlorophyll synthesis and electron transport in plants.
- **Manganese**: This is also a micronutrient essential for photosynthesis and enzyme function.

### Step 4: Conclusion
Based on the analysis, the only element that is not essential for plant growth is **Cadmium**. Therefore, the correct answer is Cadmium.

### Final Answer:
**Cadmium** is not an essential mineral element for plants.

---