Final answer:
The best physical security practice is to lock up sensitive documents and materials when not in use. Other practices like sharing ID badges or discussing sensitive information in public are not recommended for data protection.
Step-by-step explanation:
A key aspect of maintaining security, both online and offline, involves good physical security practices. The option that represents a good physical security practice is c) Locking up sensitive documents and materials when not in use. This is essential to protect sensitive information from unauthorized access. It's important to note that leaving your computer unlocked (option a), sharing your work ID badge (option b), and discussing classified information in public areas (option d) are all poor security practices that could lead to data breaches and other security issues. To further protect one's data, individuals should be vigilant in various aspects such as protecting credit cards, mailboxes, wallets, using strong passwords and PINs, utilizing anti-virus software, and informing banks about changes in address or phone details.