听力原文： As the leader of a department, one of the responsibilities of being a part of the management team is that you will at times need to come into the office before any other staff member and leave after all other staff members as well. In order to keep our company safe from unwanted intruders or from easily disclosing any of our confidential trade secrets, a management security system has been introduced in addition to our regular security system. When you come in early in the morning, before you access the management information page, you will be requested to enter a supervisory access code. This code will change on a daily basis. Therefore i recommend that you memorize the access code daily. First, this will reduce the odds of the code entering the hands of a renegade worker, and it will also help you to access the system more quickly.
Who is the audience of this talk？

A. Security guards.
B. Department heads.
C. All employees.
D. Sales staff.