Ethel operates a business. To every employee she hires she makes what she calls her "four golden promises," shown in choices A-D below. Which of the golden promises subjects Ethel to a legal detriment?
A.Ethel promises never to discharge an employee because he arrives a few minutes late to work.
B.Ethel promises never to discharge an employee because of his religion.
C.Ethel promises never to discharge an employee because she has joined a union.
D.Ethel promises never to discharge an employee because he was born outside of the United States.