The correct matching is as follows: A. Plague is caused by the bacterium Yersinia pestis (4. Bacteri a). B. AIDS is caused by the Human Immunodeficiency Virus (HIV) (3. Virus). C. Baldness (specifically some forms like Tinea Capitis or ringworm of the scalp) can be caused by fungal infections (2. Fungus). D. Malaria is caused by parasites of the genus Plasmodium, which are protozoa (1. Protozoa).