Explanation
The project manager should fast-track the project to compress the project schedule and ensure the completion date is not affected by the unforeseen risk occurrence. Fast-tracking is a schedule compression technique that involves performing activities in parallel that were originally planned to be performed sequentially1. This can reduce the overall duration of the project, but it may also increase the risk and complexity of the project.
Reducing the project scope (A) may not be possible or acceptable, as it may affect the project deliverables and customer satisfaction. Increasing the project cost (B) may not be feasible or beneficial, as it may not guarantee the reduction of the project duration. Adding more project resources may not be available or effective, as it may introduce new challenges such as coordination, communication, and training. References: 1: PMBOK Guide, 6th Edition, p. 215.