What are the two types of wiping techniques used during surface sampling?

The selection of S-pattern and decreasing concentric square as the correct answer is appropriate because these techniques are specifically designed to effectively sample surfaces for contamination in CBRN reconnaissance operations.

The S-pattern technique involves moving the sampling medium in an S-shaped path across the surface, which allows for a thorough and systematic collection of potential contaminants. This method ensures that a larger area is covered while minimizing the risk of missing critical spots where harmful substances might be present.

The decreasing concentric square technique is another effective method, where the sampling starts from a central point and moves outward in progressively larger squares. This method is valuable as it can help to minimize the spread of contaminants by concentrating sampling efforts around potential hotspots while still ensuring a comprehensive coverage of the area.

Both of these techniques are structured and methodical, aligning well with the principles of effective sampling needed to gather accurate data on the presence of CBRN agents. They are reliable in various operational environments and contribute significantly to the data integrity required in reconnaissance operations.