**Core Concept**
Schistosomiasis, also known as bilharzia, is a chronic disease caused by parasitic flatworms (schistosomes) that infect the urinary or gastrointestinal tract. Effective treatment involves antiparasitic medications that target the schistosome life cycle.

**Why the Correct Answer is Right**
Praziquantel is the drug of choice for schistosomiasis due to its high efficacy in killing adult worms and inhibiting egg-laying. It works by binding to the calcium channels in the parasite's cell membrane, leading to an influx of calcium ions and subsequent muscle contraction, ultimately causing the parasite's death. Praziquantel is effective against all species of schistosomes and is the recommended treatment according to the World Health Organization (WHO).

**Why Each Wrong Option is Incorrect**
**Option A:** Oxamniquine is an alternative treatment for schistosomiasis, particularly for **Schistosoma mansoni** infections. However, it is not the first-line treatment.
**Option B:** Metronidazole is an antibiotic used to treat various bacterial and protozoal infections but is not effective against schistosomes.
**Option C:** Albendazole is an antiparasitic medication used to treat a range of worm infections, but it is not the preferred treatment for schistosomiasis.

**Clinical Pearl / High-Yield Fact**
Praziquantel is often administered in a single dose, but the treatment may need to be repeated 4-6 weeks after the initial dose to ensure clearance of all parasites and prevent re-infection.

**Correct Answer: C. Praziquantel**