Which statement correctly matches a direct life cycle with one human parasite example and an indirect life cycle with a different parasite?

• A. Direct life cycle: Taenia solium; Indirect life cycle: Wuchereria bancrofti
• B. Direct life cycle: Plasmodium falciparum; Indirect life cycle: Ascaris lumbricoides
• C. Direct life cycle: Enterobius vermicularis; Indirect life cycle: Schistosoma mansoni
• D. Direct life cycle: Ascaris lumbricoides; Indirect life cycle: Echinococcus granulosus

Answer: (C)

Direct life cycles complete all development within a single host and the surrounding environment, with no obligatory intermediate host. Indirect life cycles require one or more extra hosts to complete development before infecting the final host.

Enterobius vermicularis, the pinworm, is a classic direct-life-cycle parasite in humans. Infected people pass eggs in feces; the eggs contaminate environment, another person may ingest them, and the cycle continues without any other organism required for development.

Schistosoma mansoni, by contrast, needs an intermediate host—a freshwater snail. The cycle starts with eggs excreted in human feces that reach water, hatch into miracidia, infect snails, and develop there into cercariae. These cercariae then shed into water and can penetrate human skin to start the cycle anew. This two-host progression defines an indirect life cycle.

The pairing in this option stays consistent with one parasite having a direct life cycle and another, different parasite, having an indirect one, making it the best-matching choice.