Answer:
stratified sampling
Explanation:
Note, in the stratified sampling sample method, the population is divided into smaller strata or smaller groups, and then a sample is selected randomly.
In this scenario, the population is a day (24 hours), so dividing the population (day) into three parts; morning, afternoon, and evening represents the various strata. Hence, since Charlotte, the researcher measures her stress level at 2 randomly selected times during each part of the day, she would be using the stratified sampling method.