Option 1: Leprosy - This is incorrect. Leprosy, also known as Hansen`s disease, is caused by the bacterium Mycobacterium leprae, not by a fungus.
Option 2: Leukoderma - This is incorrect. Leukoderma, also known as vitiligo, is a condition where patches of skin lose their pigment. It is not caused by a fungus but is thought to be an autoimmune disorder.
Option 3: Ringworm - This is the correct answer. Ringworm, also known as dermatophytosis, is a common fungal infection of the skin, nails, and scalp. It is caused by various types of fungi, including dermatophytes.
Option 4: Scabies - This is incorrect. Scabies is a highly contagious skin infestation caused by tiny mites, not by a fungus.
Therefore, the correct answer is option 3, Ringworm. Ringworm is caused by a fungus, not by bacteria or mites.