Answer & Explanation:
Correct Answer: B) It can be verified in polynomial time, but no polynomial-time solution is known for a deterministic machine.
Explanation: NP-Complete problems represent the hardest problems in the NP class. If a correct solution is provided, a standard computer can verify its correctness quickly (in polynomial time). However, actually finding that solution from scratch currently requires exponential time because no fast deterministic algorithm has ever been discovered.