[A]: Senescence is induced by the application of cytokinin in plants.
[R]: Cytokinin promotes the breakdown of chlorophyll, proteins and nucleic acid.

Options

A. If both A and R are true and R is the correct explanation of A
B. If both A and R are true but R is not the correct explanation of A
C. If A is true and R is false
D. If both A and R are false

Answer

To solve the question regarding the assertion and reason related to senescence and cytokinin in plants, we will analyze both statements step by step.

### Step-by-Step Solution:

1. **Understanding Senescence**:
- Senescence is the process of aging in plants. It involves the gradual deterioration of plant tissues, leading to the eventual death of the plant or its parts (like leaves).
- During senescence, there is a breakdown of chlorophyll, proteins, and nucleic acids, which is often visible as yellowing of leaves.

2. **Role of Cytokinins**:
- Cytokinins are a class of plant hormones that play a crucial role in regulating cell division and growth.
- Importantly, cytokinins are known to delay the process of senescence. They do this by preventing the breakdown of essential components like chlorophyll, proteins, and nucleic acids.

3. **Analyzing the Assertion**:
- The assertion states: "Senescence is induced by the application of cytokinin in plants."
- This statement is **false** because cytokinin does not induce senescence; rather, it delays it.

4. **Analyzing the Reason**:
- The reason states: "Cytokinin promotes the breakdown of chlorophyll, proteins, and nucleic acid."
- This statement is also **false** because cytokinins actually prevent the breakdown of these components, thereby delaying senescence.

5. **Conclusion**:
- Since both the assertion and the reason are false, the correct answer to the question is that both statements do not accurately represent the relationship between cytokinin and senescence.

### Final Answer:
Both the assertion and the reason are false.