Which of the following diseases can be caused by either a bacterial or a viral infection?

• A. Ringworm
• B. Malaria
• C. Athlete's foot
• D. Pneumonia

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the nature of each disease listed. Ringworm and Athlete's foot are fungal infections, while Malaria is caused by a protozoan parasite. Pneumonia, however, can be caused by multiple types of pathogens including bacteria, viruses, and sometimes fungi.
2. Step 2: Identify the causative agents for each disease. Ringworm and Athlete's foot are caused by dermatophyte fungi, Malaria is caused by Plasmodium species (protozoa), and Pneumonia can be caused by bacteria such as Streptococcus pneumoniae or viruses like influenza virus.
3. Step 3: Recognize that the question asks for a disease that can be caused by either bacterial or viral infection. This means the disease must have both bacterial and viral etiologies.
4. Step 4: Compare the diseases against this criterion. Since Ringworm and Athlete's foot are fungal, and Malaria is protozoan, they do not fit. Pneumonia fits because it can be caused by both bacteria and viruses.
5. Step 5: Conclude that Pneumonia is the correct answer because it can be caused by either bacterial or viral infections, unlike the other diseases listed.