Answer:
D
Step-by-step explanation:
We can go through each form of sampling and see where this scenario fits.
- Simple random sampling is simply taking a random percentage of the population. In this case, with the population being students in Carol's school, this would entail taking a random sample from her school. As her friends are not randomly selected, this does not fit
- Systematic random sampling means that every nth item is selected. For example, if Carol took every 10th person at her school, this would fit. However, as her friends are not selected by Carol choosing every 5th or 10th person at school (or something like that), this does not fit.
- Stratified random sampling means that different subgroups of the population are selected, and once those are selected, it is randomized to see who out of the subgroup is selected. For example, if Carol took all the men and women in her school and chose 50 random men and 50 random women, this would work. Although Carol's friends may define a subgroup of the population here, she is not asking anyone outside of that subgroup here, so this does not fit.
As none of these fit, the only answer left is D
