Answer:
"Members of a population are organized in clusters, each of which is representative of the population, and then whole clusters are randomly selected to make up the sample"
Explanation:
In cluster random sampling, "the population is divided, usually geographically, into groups that generally have the same size. A certain number of groups are randomly chosen, and every individual in the chosen groups are chosen for the sample."
In accord with this logic, the second choice, "Members of a population are organized in clusters, each of which is representative of the population, and then whole clusters are randomly selected to make up the sample" seems to be correct.
NOTE: This may not be the correct answer. I am simply basing my answer on the definition I have learnt.