Final answer:
The statement 'You may not ask an interviewee if he or she is married or has children' is the best example of a law, as it pertains to anti-discrimination laws in employment.
Step-by-step explanation:
The best example of a law among the options provided is:
B. You may not ask an interviewee if he or she is married or has children.
This statement refers to laws related to employment and discrimination, which in many countries, including the United States, make it illegal to ask certain personal questions that are irrelevant to the candidate's ability to perform the job. Questions that can lead to discrimination based on marital status, gender, race, and other protected characteristics are generally off-limits during the interview process.
The other statements A, C, and D are either ethical guidelines or practical advice, rather than actual enforced laws.