Malaria transmission cycle via mosquito vector and Plasmodium parasite

Steps:

• Recall Plasmodium life cycle: sporozoites injected by mosquito into human bloodstream, develop in liver and red blood cells, form gametocytes ingested by mosquito during blood meal.
• Identify mosquito role as vector transmitting parasite stages between hosts.
• Evaluate diagrams for bidirectional flow: human infection by mosquito bite, parasite maturation in human, transmission back via mosquito.
• Select diagram showing accurate sequence without errors like direct human-to-human spread.

Why C is correct:

• Depicts mosquito injecting sporozoites into human (causing infection) and ingesting gametocytes during bite, matching Plasmodium's defined vector-host cycle in parasitology.

Why the others are wrong:

• A shows direct human-to-human transmission, ignoring mosquito vector.
• B illustrates parasite development solely in mosquito, omitting human host role.
• D reverses roles, portraying human as vector and mosquito as primary host.

Final answer: C