**Core Concept**
Pulmonary eosinophilia syndrome is a condition characterized by an intense eosinophilic infiltration of the lungs, often associated with parasitic infections. This condition is a type of hypersensitivity reaction, where the immune system overreacts to the presence of a foreign antigen, leading to an accumulation of eosinophils in the affected tissue.

**Why the Correct Answer is Right**
The correct answer is a parasite that causes pulmonary eosinophilia syndrome through a type II hypersensitivity reaction. This reaction is mediated by IgE antibodies, which bind to the parasite's surface antigens and trigger the release of histamine and other chemical mediators from mast cells. The increased levels of histamine and other mediators cause the blood vessels to dilate, leading to increased permeability and leakage of eosinophils into the lung tissue.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not a parasite that commonly causes pulmonary eosinophilia syndrome. While this parasite can cause a range of clinical symptoms, it is not typically associated with this specific condition.

**Option B:** This option is incorrect because it is a type of bacteria, not a parasite, and is not commonly associated with pulmonary eosinophilia syndrome.

**Option C:** This option is incorrect because it is a type of virus, not a parasite, and is not commonly associated with pulmonary eosinophilia syndrome.

**Clinical Pearl / High-Yield Fact**
The Loeffler's syndrome, also known as pulmonary eosinophilia syndrome, is a classic example of a type II hypersensitivity reaction. It is often associated with parasitic infections, such as the Strongyloides stercoralis.

**Correct Answer:** A. **Strongyloides stercoralis**