[A]: Foot and mouth disease causes ulcer- ation in mouth and hoof clefts.
[R]: Foot and mouth disease is highly conta- gious

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 statements about foot and mouth disease, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Assertion Statement**:
- The assertion states that "Foot and mouth disease causes ulceration in mouth and hoof clefts."
- This statement is true because foot and mouth disease is known to cause lesions and ulcers in the mouths and hooves of affected animals, particularly cloven-hoofed animals.

2. **Identify the Reason Statement**:
- The reason states that "Foot and mouth disease is highly contagious."
- This statement is also true as foot and mouth disease is known for its high contagion rate, spreading easily among susceptible animals.

3. **Evaluate the Relationship**:
- Now we need to determine if the reason statement correctly explains the assertion statement.
- While both statements are true, the reason that the disease is highly contagious does not explain why it causes ulceration in the mouth and hoof clefts. The ulceration is a symptom of the disease, not a result of its contagious nature.

4. **Conclusion**:
- Since both the assertion and reason are true, but the reason does not provide a correct explanation for the assertion, we conclude that the correct answer is: "Both assertion and reason are true, but reason is not the correct explanation of assertion."

### Final Answer:
The correct option is: **Both assertion and reason are true but reason is not the correct explanation of assertion.**

---