Choice A is correct.

Asking customers which new option they might order in the future does not determine actual customer preferences. One restaurant may not be representative of the entire chain. Some of the new options may be more appropriate for lunch or dinner. Therefore, the following are less likely to produce valid results:

Asking a random sample of customers at all of the restaurants which new option they might order in the future.

Recording how many customers ordered each of the new options in one of the restaurants over the two-week period.

Recording how many customers ordered each of the new options for breakfast in all of the restaurants over the two-week period.