What does an Estimator primitive do?

Question: In Qiskit-style primitives, what is the Estimator mainly used for? A) Counting the number of physical cables in a quantum processor B) Estimating expectation values of observables for quantum circuits C) Drawing only circuit diagrams D) Measuring qubits without using a circuit Correct: B Explanation: The Estimator primitive is used to estimate expectation values of observables with respect to states prepared by quantum circuits. This is especially useful in variational algorithms. Topic: quantum computing / Qiskit / Estimator