**Core Concept**
Proper hand hygiene is a crucial infection control measure to prevent the spread of healthcare-associated infections (HAIs). Hand hygiene involves the use of either hand sanitizer or soap and water to eliminate microorganisms from the hands.

**Why the Correct Answer is Right**
Proper hand hygiene involves the use of soap and water when hands are visibly soiled or after using the toilet, and hand sanitizer when hands are not visibly soiled. This is because soap and water is more effective in removing dirt and organic matter, while hand sanitizer is more effective against a wider range of microorganisms. The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) recommend hand hygiene as the most effective way to prevent HAIs.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify when hand sanitizer or soap and water should be used. Proper hand hygiene requires a clear understanding of when to use each.
**Option B:** This option is incorrect because it implies that hand sanitizer is sufficient for all situations, when in fact soap and water is needed when hands are visibly soiled.

**Clinical Pearl / High-Yield Fact**
It's essential to remember the "when to use what" guideline: use soap and water when hands are visibly soiled or after using the toilet, and hand sanitizer when hands are not visibly soiled. This simple mnemonic can help you remember the correct hand hygiene procedure.

**Correct Answer:** A.