Select the correct definition of a random sample.

A.a sample that is selected from a group of people who chose whether to participate or not

B.a sample that is selected based on the researcher's judgment

C.a sample that is composed of participants who are easy to obtain

D.a sample in which individuals selected are then asked if they know others who want to participate

E.a sample in which each member of the population has a known and equal probability of being selected