4. A bank surveyed all of its 60 employees to determine the proportion who participate in volunteer activities.
Which of the following statements is true?
(A) The bank should not use the data from this survey because this is an observational study.
(B) The bank can use the result of this survey to prove that working for the bank causes employees to participate
in volunteer activities.
(C) The bank did not select a random sample of employees, so the survey will not provide the bank with useful
information
(D) The bank would have to use the survey data to construct a confidence interval in order to estimate the
proportion of employees who participate in volunteer activities.
(E) The bank does not need to use an inference procedure to determine the proportion of employees who
participate in volunteer activities because the survey was a census of all employees.