What is the subtle difference between error mitigation and correction?

Question: Which statement best distinguishes quantum error mitigation from quantum error correction? A) Error mitigation post-processes or modifies experiments to estimate less noisy expectation values, while error correction encodes logical information to actively detect and correct errors during computation B) Error mitigation requires logical qubits, while error correction works only on unencoded physical qubits C) Error mitigation completely removes noise if enough shots are used D) Error correction is a classical post-processing technique applied only after measurement Correct: A Explanation: Error mitigation aims to reduce noise bias in estimated observables without full fault tolerance. Error correction protects quantum information during the computation using encoded logical qubits, syndrome measurements, and recovery procedures. Topic: advanced quantum computing / mitigation vs correction