Answer:
Option A
Explanation:
Taking a random sample of every 100th household in the city is the best random sample for this survey as every household has to go for grocery shopping at least maybe one or twice a week. And a questionable survey or telephone survey can be used to determined which grocery store they go to and this was be able to estimate the most popular of the grocery stores without bias. The rest options especially b and d if used will produce bias which might tend to lean in favour of the mall wherein they are and not be a representative of the population's opinions.