Assess graduate students' conceptual understanding of the complexity classes P, NP, NP-complete, and NP-hard by asking for intuitive definitions, key differences, representative examples (decision vs. optimization problems), the roles of deterministic vs. nondeterministic polynomial time, the meaning and purpose of polynomial-time reductions and completeness, and brief discussion of practical implications; emphasize clear conceptual explanations and simple illustrative reasoning rather than formal proofs.