the answer is D my teacher just went over this hope this helps you
The sample for the elementary school teacher in this situation is the materials list for every third experiment.
A sample is a smaller group of the population. A sample is needed because it might not be possible or cheap to access the whole population.
It might take a long time for the teacher to read all the material lists, so she takes a sample of the material lists by only reading a third of the material lists.
To learn more about sample, please check: https://brainly.com/question/18521835