Ethylene is antagonised by

Options

A. Calcium
B. Carbon dioxide
C. Silver
D. Both B and C.

Answer

To answer the question "Ethylene is antagonised by", we will analyze the options provided and the role of ethylene in plants.

### Step-by-Step Solution:

1. **Understanding Ethylene**:
- Ethylene is a gaseous plant hormone primarily responsible for the ripening of fruits. It plays a crucial role in various plant processes, including fruit ripening, flower wilting, and leaf fall.

2. **Identifying Antagonists**:
- Antagonists are substances that counteract or inhibit the effects of another substance. In this case, we are looking for substances that inhibit the action of ethylene.

3. **Evaluating the Options**:
- **Option A: Calcium**: Calcium does not have a known antagonistic effect on ethylene. It is more involved in cell wall structure and signaling rather than inhibiting ethylene's effects.
- **Option B: Carbon Dioxide**: Carbon dioxide is known to inhibit the synthesis of ethylene and is used in storage to delay ripening. Thus, it acts as an antagonist to ethylene.
- **Option C: Silver**: Silver ions are known to effectively inhibit the action of ethylene by preventing the initiation and continuation of the ripening process. Therefore, silver also acts as an antagonist to ethylene.
- **Option D: Both B and C**: Since both carbon dioxide and silver are antagonists to ethylene, this option is correct.

4. **Conclusion**:
- Based on the analysis, the correct answer is **Option D: Both B and C** (Carbon Dioxide and Silver).

### Final Answer:
Ethylene is antagonised by both carbon dioxide and silver.