Final answer:
Decision trees are used to review activity and project risk by graphically representing possible decision paths and their potential outcomes, which include risks and rewards.
Step-by-step explanation:
The question asks which of the following methods is used to review activity and project risk: NPV, S-curves, PERT, or Decision trees. When it comes to reviewing project activities and especially assessing project risks, Decision trees are an effective tool. Decision trees provide a graphical representation of possible solutions to a decision based on various conditions and their possible consequences, including risks, rewards, and trade-offs.
NPV (Net Present Value) is used for assessing the profitability of a project by calculating the present value of cash inflows and outflows over the project's life. S-curves are graphical presentations of cumulative costs, labor hours, or other quantities plotted against time which are used for analyzing the growth and performance of a project over time. PERT (Program Evaluation and Review Technique) is a statistical tool used to manage uncertain activity times in a project schedule.
Answer: D. Decision trees