Which one is correct about probability sampling?
A.
A given size of the sample in simple random sample is drawn with the help of a ordered number chart.
B.
Sample members from a larger population are selected according to a random starting point but with a fixed, periodic interval in systematic sampling.
C.
The sample size for each sub-group can be unfixed to get representative sample in stratified Random Sample.
D.
Some of elements of selected groups is sampled and studied in one-stage cluster sampling.