**Core Concept**
Lung cancer in non-smokers is a distinct clinical entity, accounting for approximately 10-20% of all lung cancer cases. The pathogenesis of lung cancer in non-smokers is often associated with genetic mutations, environmental exposures, and specific histological subtypes.

**Why the Correct Answer is Right**
The most common lung cancer in non-smokers is adenocarcinoma, which accounts for approximately 40-50% of all lung cancer cases. Adenocarcinoma is a type of non-small cell lung cancer (NSCLC) that originates from the peripheral airways. The genetic mutations associated with adenocarcinoma in non-smokers often involve epidermal growth factor receptor (EGFR) mutations, which are more prevalent in this population.

**Why Each Wrong Option is Incorrect**
**Option A:** Squamous cell carcinoma is more common in smokers, often associated with a history of smoking and exposure to carcinogens such as asbestos.
**Option B:** Small cell lung cancer is highly aggressive and strongly associated with smoking, with a poor prognosis.
**Option C:** Large cell carcinoma is a rare subtype of NSCLC, but its incidence is not significantly higher in non-smokers compared to adenocarcinoma.

**Clinical Pearl / High-Yield Fact**
Non-smokers with lung cancer are more likely to be female, younger, and have a family history of lung cancer. Adenocarcinoma in non-smokers often presents with ground-glass opacities on imaging and may be associated with EGFR mutation testing for targeted therapy.

**Correct Answer: A. Adenocarcinoma**