Correct Option (b):
- A. Malaria is caused by Plasmodium parasites, which primarily infect and multiply within red blood cells.
- B. Filaria, caused by filarial worms, affects the lymphatic system, leading to conditions like elephantiasis, with lymph nodes being a primary site of infection.
- C. Encephalitis refers to the inflammation of the brain, often due to viral infections.
- D. Leukaemia is a cancer of the blood-forming tissues, predominantly the bone marrow, characterized by the overproduction of abnormal white blood cells.
Incorrect Options:
- Option 1 (5 3 2 1): This option incorrectly matches Filaria (B) with Muscle (3). Filaria primarily affects the lymphatic system, not muscles.
- Option 3 (4 3 5 1): This option incorrectly matches Malaria (A) with Lymph node (4). Malaria primarily affects blood cells.
- Option 4 (5 4 1 2): This option incorrectly matches Encephalitis (C) with Bone marrow (1) and Leukaemia (D) with Brain (2). Encephalitis affects the brain, and Leukaemia affects bone marrow.