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 make a cause- and- effect conclusion.

A) This was an experimental study so we conclude that wearing a suit jacket caused a male customer to be addressed faster.
B) Since this was a controlled observational study we can conclude that there was a cause- and- effect relationship.
C) This was an observational study. Since random assignment was not used, we cannot conclude that getting addressed faster was caused by wearing a suit jacket.
D) The male customers (and diners) were not selected from a larger population, so we cannot conclude that there was a cause- and- effect relationship.