**Core Concept**
Feces disinfection is crucial for preventing the spread of infectious diseases. Disinfectants used for feces should be effective against a broad spectrum of pathogens, including bacteria, viruses, and protozoa.

**Why the Correct Answer is Right**
5% cresol is the recommended disinfectant for feces due to its broad-spectrum antimicrobial activity. Cresol is a phenol derivative that disrupts the cell membranes of microorganisms, ultimately leading to their death. The 5% concentration is effective against a wide range of pathogens, including Salmonella, Shigella, and E. coli. The use of cresol for feces disinfection is also supported by its stability and ease of use.

**Why Each Wrong Option is Incorrect**
**Option A:** 1% formaldehyde is a disinfectant, but it is not the most effective choice for feces. Formaldehyde is a potent irritant and can be hazardous to human health, making it less suitable for feces disinfection.
**Option C:** 5% phenol is a disinfectant, but it is not as effective as cresol against a broad spectrum of pathogens. Phenol can also be toxic and has a strong odor, making it less desirable.
**Option D:** Isopropyl alcohol is used as a disinfectant, but it is not effective against non-enveloped viruses and some bacteria. Isopropyl alcohol also evaporates quickly, reducing its effectiveness on feces.

**Clinical Pearl / High-Yield Fact**
When disinfecting feces, it's essential to use a disinfectant that is effective against a broad spectrum of pathogens. A 5% cresol solution is a reliable choice due to its stability, ease of use, and broad-spectrum antimicrobial activity.

✓ Correct Answer: B. 5% cresol