Answer:
The correct option is B) The 20 students the researcher observed.
Explanation:
Consider the provided information.
Feeding a group of 20 students hamburgers for lunch she observed that, on average, the students committed 2.5 aggressive behaviors during their afternoon play period.
The sample space of the experiment or the random test is the set of all possible results or tests of the experiment.
Here, the possible results are the behaviors of 20 students.
Thus, the sample of the study is B) The 20 students the researcher observed.