What is the difference between a simulator and real quantum hardware?

Question: What is a key difference between a quantum simulator and real quantum hardware? A) Real hardware is affected by physical noise and device constraints B) Simulators cannot represent quantum states at all C) Real hardware always gives exact probabilities in one shot D) Simulators require actual superconducting qubits Correct: A Explanation: A simulator runs a mathematical model of a quantum circuit on classical hardware. Real quantum devices are physical systems, so their results are affected by noise, calibration, connectivity, and limited coherence. Topic: quantum computing / simulation / hardware