Sampling

Identify the sampling technique used to obtain a sample.
The Food & Drug Administration randomly selects 5 stores from each of 4 other randomly selected sections of a large city and checks food items for freshness. These stores are used as a representative sample of the entire city.
I picked stratification and it was incorrect. Help anyone?

Whatever you picked, justify it. Why do you think it's statification? A random draw does NOT bifurcate the population into "drawn" and "not drawn". It seems this is the only stratification to which you could be referring.