Answer:
c. Cluster sampling
Step-by-step explanation:
Taking into account that the exercise researcher is looking with limited resources to study a population that is divided, her best option is cluster sampling, which is a method applicable to this type of population, we could select in each group randomly her sample, the observational study is discarded because she does not have much availability of time or resources, nor would the stratified study be useful because she should select subgroups and create them to take samples and this would take more time and resources and sampling systematic is not adequate because it must have all the individuals and after having the list select the sample, but as we know, it is a process that will study the number of individuals so this option is not feasible.
10 will be your answer because 4 x 5 divided by 2 is 10
2+2+9+0+8+1+2+3+4+5+6+7+8+9 is 66
