What type of sample is removed at a single point in time from one location?

The correct answer is "grab," which refers to a type of sample that is collected from a specific location at a single point in time. This method allows for the assessment of immediate conditions at that particular moment. Grab sampling is particularly useful in situations where it is crucial to understand the characteristics of a sample as they exist instantaneously, such as in monitoring air quality or water contamination at a specific site.

In contrast, a discrete sample can refer to one taken from distinct time intervals or locations, which may not capture the immediate environmental conditions as effectively as a grab sample. Composite samples involve combining several different samples taken over time or from different locations, which provides an average concentration but may obscure any immediate variations. Continuous sampling refers to the ongoing collection of data over a period of time, which helps track changes but is not specific to a single moment or location. Therefore, grab sampling is the most accurate description for the scenario presented, as it focuses on immediate, location-specific data collection.