A breach of physical security is an unauthorized access or damage to physical assets, such as equipment, data, or personnel. Project documentation that is only kept on a removable device is the best example of a breach of physical security, because it exposes sensitive information to theft, loss, or corruption. If the removable device is not encrypted or protected, anyone who obtains it can access the project documentation and compromise the project integrity, confidentiality, or availability. Therefore, project documentation should be stored in a secure location, backed up regularly, and protected by access controls and encryption.

The other options are not examples of physical security breaches, but rather logical or administrative security breaches. System user IDs being used by multiple individuals is a violation of the principle of least privilege and accountability, which could lead to unauthorized access or misuse of system resources. Printers that do not request user authentication is a lack of proper access control, which could allow unauthorized printing or retrieval of confidential documents. Developers having full access to both development and production environments is a violation of the principle of separation of duties and environments, which could introduce errors, conflicts, or malicious code into the production system. References = CompTIA Project+ Study Guide: Exam PK0-005, 3rd Edition, Chapter 9: Security Management1; CompTIA Project+ Certification Study Guide, 3rd Edition, Chapter 9: Security Management2; Types of Security Breaches: Physical and Digital3