Use the Following Information to Answer the Question

Use the following information to answer the question. A researcher wonders whether speed of service at a diner is affected by whether a male customer is wearing a suit jacket. The researcher used the following study design to collect data: The researcher chose five diners in a large city and recorded the number of male customers that wore a suit jacket during a two week period. He also records how long it took a waiter or waitress to address the customer. He finds that male customers who wear suit jackets were addressed by the wait staff faster than male customers who did not wear a suit jacket.
-Choose the statement that correctly explains why we can or cannot generalize these results to a larger population.

A) The male customers were randomly selected to participate in the study so the results can be generalized to the larger population.
B) The male customers were not randomly assigned to wear a suit jacket so the results cannot be generalized to beyond the sample.
C) This was an observational study so results can be generalized to a larger population.
D) The male customers (and diners) were not selected from a larger population, so the results cannot be generalized beyond the sample.