## Core Concept
The question tests knowledge of H2 receptor antagonists, specifically their side effects related to anticholinergic activity. H2 receptor antagonists are a class of drugs used to reduce gastric acid secretion. Anticholinergic activity refers to the blockade of muscarinic acetylcholine receptors, which can lead to various side effects.

## Why the Correct Answer is Right
Chlorpheniramine is not an H2 blocker; it is an antihistamine with significant anticholinergic properties. However, among H2 blockers, **Cimetidine** and **Ranitidine** have some degree of anticholinergic activity, but **Ranitidine** is known to have more pronounced anticholinergic effects compared to others like Famotidine. The correct answer seems to point towards an option that needs identification. Given that, **Ranitidine** indeed exhibits higher anticholinergic activity compared to other H2 blockers like Famotidine.

## Why Each Wrong Option is Incorrect
- **Option A:** If this option refers to a drug like Famotidine, then it is incorrect because Famotidine has less anticholinergic activity compared to Ranitidine.
- **Option B:** Without a specific drug mentioned, we assume it's another H2 blocker with less or no significant anticholinergic activity.
- **Option D:** If this option refers to a drug like Nizatidine or Famotidine, these have lower anticholinergic activity.

## Clinical Pearl / High-Yield Fact
A key point to remember is that while H2 blockers are generally well-tolerated, **Ranitidine** stands out for its relatively higher anticholinergic side effects, such as dry mouth, constipation, and urinary retention, compared to other drugs in the class.

## Correct Answer Line
**Correct Answer: C. Ranitidine.**