Which of the following removes contamination most effectively?

Washing with soap and water is the most effective method for removing contamination, especially in the context of radioactive materials. This process helps to dissolve and displace contaminants from surfaces, ensuring that both the radioactive particles and any other dirt or debris are washed away. The soap aids in emulsifying contaminants, which can make it easier to remove them from skin or other surfaces when rinsed with water.

This method is particularly effective because it not only physically removes contaminants but can also neutralize certain types of chemicals present in the contamination, making it safer for individuals and preventing further spread of the material. Additionally, washing is generally a thorough approach that can reach into small crevices and difficult-to-access areas, where contamination might otherwise linger.

Other methods, such as dusting off surfaces or using a vacuum cleaner, may help to remove some contamination, but they are often less effective for thoroughly eliminating all residues. Dusting can leave behind finer particles, and while vacuuming may remove loose contaminants, it may not address those that are more securely adhered to surfaces. Applying chemical solvents can be effective for specific types of chemical contaminants, but their effectiveness on radioactive materials is less predictable and may not be as comprehensive as soap and water.