Select the correct pairs of diseases and their respective symptoms.
i. Elephantiasis - swollen limbs especially legs, enlargement of lymph vessels and lymph nodes.
ii. Malaria - Infected skin which shows enlarged red rings, nails become thick, discoloured and disfigured.
iii. Dermatophytosis - Cyclic high fever followed by sweating and sudden shivering every two days or three days.
iv. Pneumonia - Dyspnea, cough produces yellow or greenish sputum or phlegm.
Choose the correct option.

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.