Final answer:
PERT is a project management tool used to schedule project tasks but is not used for queueing problems, which are different in nature and require different analytical techniques.
Step-by-step explanation:
The Program Evaluation and Review Technique (PERT) is a project management tool used to plan, schedule, and control complex tasks. PERT is commonly utilized in situations where the time required to complete different components of a project can be estimated. Answering the student's question, PERT is not used for queueing problems (D). Queueing problems involve analyzing systems in which customers arrive to receive a service and wait if the service is not immediately available, which is very different from the project planning and scheduling activities that PERT handles.
PERT is not designed for evaluating individual performance (A), and it is not typically used for tasks that are considered easy (B), as the complexity and resources required for a PERT chart would not be justified for simple tasks. However, these are not the reasons PERT would be inapplicable to queueing problems. The nature of queueing problems, which require different analytical techniques, makes PERT unsuitable for this particular application.