**Core Concept**
Chlorhexidine is a broad-spectrum antiseptic that is commonly used for hand washing, especially in healthcare settings. Its mechanism involves binding to bacterial cell membranes, disrupting the cell wall and ultimately leading to cell death.

**Why the Correct Answer is Right**
Chlorhexidine is effective against a wide range of microorganisms, including bacteria, viruses, and fungi. It is particularly useful for hand washing because it has a residual effect, providing protection against infection for several hours after application. Chlorhexidine works by disrupting the bacterial cell membrane, ultimately leading to cell death. The World Health Organization (WHO) recommends the use of chlorhexidine for hand washing in healthcare settings.

**Why Each Wrong Option is Incorrect**
**Option A:** Isopropyl alcohol is an effective disinfectant, but it is not suitable for hand washing because it can be toxic to the skin and mucous membranes at high concentrations. It also has a short duration of action and does not provide a residual effect.

**Option B:** Lysol is a brand name for a household disinfectant that contains a mixture of chemicals, including benzalkonium chloride. While it can be effective against some microorganisms, it is not suitable for hand washing due to its potential toxicity and lack of residual effect.

**Option C:** Cresol is a phenolic compound that has been used as a disinfectant, but it is not commonly used for hand washing due to its toxicity and potential for skin irritation.

**Option D:** Glutaraldehyde is a potent disinfectant, but it is not suitable for hand washing due to its high toxicity and potential for skin and respiratory irritation.

**Clinical Pearl / High-Yield Fact**
When selecting an antiseptic for hand washing, consider the duration of action, residual effect, and potential for skin irritation. Chlorhexidine is a reliable choice for hand washing in healthcare settings due to its broad-spectrum activity and residual effect.

**Correct Answer: A. Chlorhexidine**