Matching diseases to their causative pathogens

Steps:

• Recall that pathogens are disease-causing agents like bacteria, viruses, or protozoa.
• Identify AIDS cause: HIV virus.
• Identify malaria cause: Plasmodium protozoan, mosquito vector.
• Identify syphilis cause: Treponema pallidum bacterium.

Why D is correct:

• Syphilis is caused by the bacterium Treponema pallidum, per microbiology definitions of bacterial pathogens.

Why the others are wrong:

• A: AIDS is caused by HIV virus, not bacterium.
• B: AIDS is caused by HIV virus, not insect.
• C: Malaria is caused by Plasmodium protozoan, not insect.

Final answer: D