Which of the Following Is Most Likely to Result in Front-End

Which of the following is most likely to result in front-end disparate impact job discrimination?

A) A company puts a notice into a job announcement that the job is very physically demanding and those without very good physical health should not apply.
B) A company decides to weed out many of the applications it has by eliminating those under and over a certain age.
C) A company decides to fill a new position by asking current employees to make personal referrals.
D) A religious institution decides not to consider applicants who do not have a professed commitment to that specific religion.