What type of sample is collected to characterize soil conditions at a specific location?

The correct choice for characterizing soil conditions at a specific location is a discrete sample. Discrete sampling involves collecting a sample from a specific and defined point in the soil, which allows for an accurate representation of the conditions at that exact location. This type of sampling is crucial for assessing localized properties such as contaminant levels, pH, moisture content, and soil structure.

In contrast, composite sampling, which combines multiple discrete samples from different locations to form a single sample, may not provide the precision needed for site-specific analysis. Grab sampling, while it can indicate conditions at that moment, often refers to a one-time collection that may not represent variations in the area unless multiple grabs are taken from different locations. Systematic sampling follows a predetermined pattern which can help in understanding trends over a wide area but may overlook localized variations important in soil characterization. Thus, for a focused examination of soil at a very specific site, discrete sampling is the most appropriate method.