(d) : Wuchereria bancrofti is a dreaded human parasite. It is a digenetic parasite completing its life cycle in two hosts, the final host is man harbouring the adult worm.The disease passes through four stages in human beings:In the first stage, the patient has increased eosinophils, enlarged lymph nodes. Second or carrier stage is symptomless.Third stage is characterised by filarial fever, inflammation of lymph nodes (lymphadenitis) and lymph vessels (lymphangiectasis) and reversible lymphoedema (excess fluid in tissues due to obstruction of lymph vessels) in various body parts. The fourth or final stage is manifestated by lymphoedema accompanied by thickening of subcutaneous tissues and skin so that there is permanent swelling mostly offeet, legs, thighs, scrotal sacs, breast etc. It is called elephantiasis.