The correct answer is B. Large and complex projects.
PERT (Program Evaluation and Review Technique) is a network analysis technique used in project management to estimate the time required to complete a project. It is mainly useful for large and complex projects with many interdependent tasks. PERT can help to identify the critical path, which is the sequence of tasks that must be completed on time in order to complete the project on time. PERT can also help to estimate the probability of completing the project on time and within budget.
A. Small projects are typically not complex enough to require the use of PERT.
C. Research and development projects are often complex, but they are not always well-defined. This can make it difficult to use PERT to estimate the time required to complete them.
D. Deterministic activities are those that have a known and certain duration. PERT is not necessary for these types of activities.