The critical path is the sequence of tasks that determines the minimum project duration. It is the longest path through the network diagram and has the least amount of slack or float. Based on the provided network diagram, the critical path is A-C-G-K-M, which has the longest total duration when adding up the individual task durations. Reference = The concept of the critical path is covered in the CompTIA Project+ Certification Study Guide1. For more detailed information on how to calculate and identify the critical path in project management, you can refer to the study guide and other project management resources2.

Operational security is the process of identifying, protecting, and controlling sensitive information and activities from unauthorized access or disclosure. Operational security includes background screenings for personnel who need to access classified or restricted information or resources, as well as implementing policies and procedures to prevent leaks, breaches, or espionage. Operational security is essential for government projects that involve national security, defense, intelligence, or law enforcement.
Operational security is different from data security, which is the process of safeguarding data from unauthorized access, use, modification, or destruction. Data security includes encryption, authentication, authorization, backup, and recovery of data. Operational security is also different from physical security, which is the process of securing physical assets, such as equipment, data, or personnel, from unauthorized access or damage. Physical security includes locks, alarms, cameras, guards, and fences. Operational security is also different from digital security, which is the process of protecting digital devices, networks, and systems from cyberattacks, malware, or hacking. Digital security includes firewalls, antivirus, VPN, and passwords. Reference = CompTIA Project+ Study Guide: Exam PK0-005, 3rd Edition, Chapter 9: Security Management1; CompTIA Project+ Certification Study Guide, 3rd Edition, Chapter 9: Security Management2; What is Operational Security (OPSEC)?3

Videoconference is the best tool to use when conducting project meetings across time zones, as it allows real-time communication, visual cues, screen sharing, and collaboration among the participants. Videoconference can also help build rapport and trust among the team members, and reduce the risk of misunderstandings or miscommunication. Videoconference tools such as Zoom, Skype, or Google Meet can also accommodate different time zones by showing the local time of each participant and allowing them to schedule meetings in advance12.

Explanation
Submit a change request to the change control board. The project manager should submit a change request to the change control board (CCB) if they realize that the project will not be completed on time due to resource constraints. A change request is a formal proposal to modify any aspect of the project, such as scope, schedule, cost, quality, or resources. A change request must be submitted to the CCB, which is a group of stakeholders who are authorized to review and approve changes. Submitting a change request can help to document the impact of the resource constraints on the project and seek approval for any corrective actions or preventive actions12

Mitigate is a risk strategy that involves taking actions to reduce the probability or impact of a risk. By applying new updates to a program in a sandbox environment, the software engineer is testing the changes before implementing them in the actual system, thus minimizing the chance of errors or failures that could affect the project1.