Assertion (A): Filariasis is commonly called elephantiasis.
Reason (R): Lymphoedema of legs is the symptom of filariasis.

Options

A. Both A and R are true and R is the correct explanation for A.
B. Both A and R are true, but R is not the correct explanation for A.
C. A is true and R is false.
D. A is false and R is true.

Explanation

### Step-by-Step Solution:

1. **Understanding the Assertion (A)**: The assertion states that "Filariasis is commonly called elephantiasis."
- Filariasis is indeed a disease caused by parasitic worms, specifically filarial worms. One of the most recognizable forms of this disease is characterized by severe swelling, particularly in the legs, which leads to the term "elephantiasis" due to the resemblance of the swollen limbs to that of an elephant.

2. **Understanding the Reason (R)**: The reason states that "Lymphoedema of legs is the symptom of filariasis."
- Lymphoedema refers to the swelling that occurs due to the accumulation of lymph fluid, which is a common symptom in filariasis. The filarial worms cause damage to the lymphatic system, leading to this condition.

3. **Analyzing the Relationship**: Now we need to analyze the relationship between the assertion and the reason.
- The assertion is true because filariasis is indeed commonly referred to as elephantiasis.
- The reason is also true as lymphoedema is a significant symptom of filariasis.

4. **Conclusion**: Since both the assertion and the reason are true, and the reason correctly explains the assertion, we can conclude that both statements are accurate.

### Final Answer:
Both the assertion (A) and the reason (R) are true, and the reason correctly explains the assertion.

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