These two actions can help mitigate the risk of staff turnover during the course of a large multi-year project, because they can increase the satisfaction, motivation, and loyalty of the project team members. A recognition program can show appreciation and gratitude for the team members' efforts and achievements, and provide positive reinforcement for their desired behavior. Training, mentoring and coaching can improve the skills and performance of the team members, and provide them with opportunities for learning and growth. These actions can also foster a positive and collaborative team culture, and enhance the trust and communication between the project manager and the team members. The other options are not effective actions to mitigate the risk of staff turnover, because they may not address the root causes or consequences of the risk, or they may create more problems or risks. Increasing the trained staff to create back-up for resources may not be feasible or cost-effective, and it may create redundancy, confusion, or conflict among the team members. Meeting with management to discuss dividing the project into smaller projects may not be possible or desirable, and it may affect the scope, quality, or benefits of the project. Convincing senior management to hire third-party staff may not be beneficial or reliable, and it may increase the complexity and risk of the project. References: Positive Reinforcement | PMI - Project Management Institute, [The Mindful Project Manager's Guide To Team Motivation: 11 ... - Planio].