Which method is NOT used to determine the depth of a pit?

The method that is not used to determine the depth of a pit is sanding the area. This choice is based on the nature of the task involved in determining pit depth.

Making a plaster cast is a technique that can capture the dimensions of a pit, providing a physical representation of its depth and shape. Using ultrasound is a non-destructive testing method that uses sound waves to measure the distance to the bottom of a pit, providing accurate depth readings. Eddy current testing is another advanced method that can be used to assess the depth and integrity of materials, particularly in metal structures, by measuring the electrical conductivity changes in the area.

Sanding the area does not provide any accurate or reliable information about the depth of a pit as it simply alters the surface texture and may remove material without measuring depth. Sanding is not an established method for pit measurement and does not contribute to understanding the depth, highlighting why it is the correct response in this context.