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 make a cause- and- effect conclusion.

A) This was an observational study. Since random assignment was not used, we cannot conclude that getting hired was caused by wearing a red tie.
B) Since this was a controlled observational study we can conclude that there was a cause- and- effect relationship.
C) The interviewees (and companies where they were interviewed) were not selected from a larger population, so we cannot conclude that there was a cause- and- effect relationship.
D) This was an experimental study so we conclude that wearing a red tie caused an interviewee to be hired.