The correct answer is D. Sample.
Explanation
The sample is the name how is known a representative portion of a population from which you want to obtain some information for an investigation. This sample will allow us to know in detail how a phenomenon occurs in a portion of the population that is to be studied. In Kevin's case, he takes a sample group of 50 students because with this group he can already learn general information about students' attitudes toward general education requirements on his campus. That is, this small group is going to show you the trends that all students have in a smaller proportion. Therefore, the correct answer is the D. Sample.
