Which of the following is most important when washing hands properly to reduce microbial contamination?

• A. Drying hands on shared towels
• B. Using only water without soap
• C. Rinsing hands quickly with cold water only
• D. Scrubbing all surfaces of the hands with soap for at least 20 seconds

Answer: (D)

Verified step by step guidance

1. Understand that the goal of handwashing is to physically remove and chemically kill microbes on the skin to reduce contamination.
2. Recognize that soap plays a critical role because it helps break down oils and dirt that harbor microbes, allowing them to be washed away more effectively than water alone.
3. Note that scrubbing all surfaces of the hands ensures that microbes are dislodged from areas that are commonly missed, such as between fingers and under nails.
4. Acknowledge that the duration of scrubbing (at least 20 seconds) is important because it provides enough time for the soap to act and for mechanical friction to remove microbes.
5. Understand that drying hands properly is important, but using shared towels can reintroduce microbes, and rinsing quickly with cold water or using only water without soap is insufficient for effective microbial removal.