Which of the following group represents all beneficial elements ?

Options

A. Na, Si, Se, Ag
B. Na, Se, Cu, Co
C. Na, Si, Co, Se
D. Na, Ne, Se, Co

Answer

To solve the question "Which of the following group represents all beneficial elements?", we will analyze the elements mentioned and determine their roles in plant biology.

### Step-by-Step Solution:

1. **Identify the Elements**: The elements mentioned in the video are sodium (Na), silicon (Si), selenium (Se), silver (Ag), copper (Cu), and cobalt (Co).

2. **Evaluate Sodium (Na)**: Sodium is known to play a role in chlorophyll synthesis and is essential for various physiological processes in plants. Thus, it is beneficial.

3. **Evaluate Silicon (Si)**: Silicon is recognized for its role in enhancing stress tolerance in plants. It helps in strengthening plant cell walls and is considered beneficial.

4. **Evaluate Selenium (Se)**: Selenium is involved in stress tolerance and growth regulation in plants. It is classified as a beneficial element.

5. **Evaluate Silver (Ag)**: Silver is known for its antimicrobial properties but is not produced internally by plants. It is used externally and does not contribute to plant growth directly, making it less beneficial in the context of essential nutrients.

6. **Evaluate Copper (Cu)**: Copper is important for lignin synthesis and plays a role in photosynthesis, albeit in small amounts. It is considered a beneficial element.

7. **Evaluate Cobalt (Co)**: Cobalt is essential for growth metabolism and is classified as a beneficial element.

8. **Compile the Beneficial Elements**: From the evaluation, the beneficial elements identified are sodium (Na), silicon (Si), selenium (Se), copper (Cu), and cobalt (Co). Silver (Ag) is excluded as it does not contribute to internal plant processes.

9. **Select the Correct Group**: Based on the analysis, the group that contains only beneficial elements is the one that includes sodium, silicon, selenium, copper, and cobalt, but excludes silver.

### Conclusion:
The correct option that represents all beneficial elements is the one that includes sodium, silicon, selenium, copper, and cobalt, while excluding silver.