A researcher separates the area of a forest into 1,000 small regions. The researcher collects data on all of the trees in each of a sample of 20 small regions. Which sampling method is being used?

Judgment sampling, or purposive sampling, involves selecting samples based on the researcher's judgment about which individuals will be most useful or representative. This method does not apply here, as the researcher is not selecting specific regions based on judgment, but rather sampling defined clusters.

Quota sampling requires the researcher to ensure certain characteristics are represented within the sample. This method typically involves non-random selection until specific quotas are met. In the given situation, the researcher does not appear to enforce quotas for specific characteristics but is sampling whole regions instead.

Simple random sampling entails selecting individuals from the entire population in such a way that each individual has an equal chance of being chosen. In this case, since the researcher is sampling entire regions rather than individuals, this method does not apply.