Use the Following Information to Answer the Question

Use the following information to answer the question. A researcher wonders whether receiving a job offer is effected by whether an interviewee wears a red tie. The researcher used the following study design to collect data: The researcher chose five large companies in a large city and observed the tie color of all interviewees during a two week period. He also records whether the person was hired by the company. He finds that interviewees who wear red ties are more likely to be hired than interviewees who do not wear red ties.
-Choose the statement that correctly explains why we can or cannot generalize these results to a larger population.

A) The interviewees were not randomly assigned to wear a red tie to the interview so the results cannot be generalized to beyond the sample.
B) The interviewees (and companies where they interviewed) were not selected from a larger population, so the results cannot be generalized beyond the sample.
C) The interviewees were randomly selected to participate in the study so the results can be generalized to the larger population.
D) This was an observational study so results can be generalized to a larger population.