Businesspeople need formal standards upon which to base decisions regarding ethical issues. Many companies have established a corporate ethics code. In ExxonMobil's Standards of Business Conduct, company guidelines state that "No one in the ExxonMobil organization has the authority to make exceptions to these policies [on business conduct]. Regardless of how much difficulty we encounter or pressures we face in performing our jobs, no situation can justify their willful violation." This example highlights the fact that corporate ethics codes require which of the following in order to help employees do the right thing in difficult circumstances?

a. Assembling an independent audit staff

b. Monitoring and enforcement by top management

c. Reviewing and discussing expectations with employees regularly

d. Ensuring a substantial majority of the Board of Directors are nonemployees