**Core Concept**
Cresol (phenol derivative) is a potent disinfectant effective against bacteria, including *Vibrio cholerae*, the causative agent of cholera. Its efficacy in degrading bacterial cell walls and disrupting microbial viability makes it particularly suitable for treating fecal matter in public health settings.

**Why the Correct Answer is Right**
Cresol is highly effective in inactivating *Vibrio cholerae* in stool samples due to its strong bactericidal action. It acts by denaturing bacterial proteins and disrupting cell membranes. In field settings, especially in resource-limited areas, cresol is preferred over other agents because it is inexpensive, readily available, and effective at low concentrations. It is specifically recommended by WHO and public health guidelines for disinfecting human waste to prevent fecal-oral transmission.

**Why Each Wrong Option is Incorrect**
Option A: Bleaching powder (calcium hypochlorite) is effective but less stable and requires proper mixing; it may not be as reliable in all environmental conditions.
Option C: Phenol is toxic and less safe for use on human waste; it is not recommended for direct application on stool due to high toxicity and poor safety profile.
Option D: Lime has limited bactericidal activity and is ineffective against *Vibrio cholerae* at typical doses; it primarily alters pH and does not reliably disinfect.

**Clinical Pearl / High-Yield Fact**
Cresol is the **gold standard** for disinfecting cholera stool in field-level sanitation due to its balance of efficacy, safety, and cost. Always use it in a diluted form to avoid skin or environmental toxicity.

✓ Correct Answer: B. Cresol