**Core Concept**
Paragonismus westermani is a parasitic flatworm, specifically a type of lung fluke, which belongs to the family Paramphistomatidae. It is one of the several species of lung flukes that infect humans, causing respiratory problems and other systemic symptoms.

**Why the Correct Answer is Right**
Paragonismus westermani is commonly known as the lung fluke because it primarily infects the lungs of its host, causing damage to the respiratory tissues and leading to symptoms such as coughing, chest pain, and difficulty breathing. The parasite is usually ingested through contaminated food or water, and it migrates to the lungs, where it matures and lays eggs. The infection can be diagnosed through stool or sputum examination.

**Why Each Wrong Option is Incorrect**
**Option A:** Not all lung flukes are Paragonismus westermani; other species like Paragonismus skrjabini and Paragonismus perfoliatus also infect humans.
**Option B:** Tapeworms are a different class of parasites that infect the gastrointestinal tract, not the lungs.
**Option C:** Intestinal flukes, such as Fasciola hepatica, primarily infect the intestines and do not cause lung infection.
**Option D:** Liver flukes, such as Clonorchis sinensis, primarily infect the liver and bile ducts, not the lungs.

**Clinical Pearl / High-Yield Fact**
Paragonismus westermani infection can be prevented by avoiding the consumption of raw or undercooked fish and other contaminated food products.

✓ Correct Answer: A. Lung fluke