A researcher planning a survey of heads of households in a particular state has census lists for each of the 23 counties in that state. He plans to obtain a random sample from each of the counties rather than grouping all census lists together and obtaining a sample from the entire group. Which of the following statements about the resulting stratified sample are true?

I. It is not a simple random sample.
II. It will help to avoid samples that do not represent the population.
III. It provides comparative information (e. g. mean salary of County X vs County Y) that a simple random sample would not provide.

I only
I and II
I and III
I, II, and III
None of the above