Final answer:
A probability matrix (option d) is the tool used in risk management. It helps assess and prioritize risks by evaluating their occurrence likelihood and potential impact on a project.
Step-by-step explanation:
The tool used in risk management referred to in the question is probability matrices (option d). These are grid-like structures that help in assessing and prioritizing risks based on the likelihood of their occurrence and their potential impact on the project. Other options, such as a WBS (Work Breakdown Structure), a project organizational chart, and critical path analysis, have different purposes. The WBS is used for breaking down projects into manageable sections, the project organizational chart displays the relationships and hierarchies within a project team, and critical path analysis is used to identify the longest path of planned activities to the end of the project and the earliest and latest that each activity can start and finish without making the project longer.