问题如下：
The best approach for creating a stratified random sample of a population involves:
选项：
A. drawing an equal number of simple random samples from each subpopulation.
B. selecting every kth member of the population until the desired sample size is reached.
C. drawing simple random samples from each subpopulation in sizes proportional to the relative size of each subpopulation.
解释：
C is correct.
Stratified random sampling involves dividing a population into subpopulations based on one or more classification criteria. Then, simple random samples are drawn from each subpopulation in sizes proportional to the relative size of each subpopulation. These samples are then pooled to form a stratified random sample.
不太明白A错在哪里？既然是subpopulation了，不就是代表了已经分层了吗？