Why are SWAP gates sometimes added during transpilation?

Question: Why might a transpiler insert SWAP gates into a quantum circuit? A) To randomly change the output B) To avoid using any physical qubits C) To move logical qubit states so required two-qubit gates can occur on connected hardware qubits D) To measure the circuit faster Correct: C Explanation: Real quantum devices often have limited connectivity. If two logical qubits need a two-qubit gate but are not mapped to connected physical qubits, SWAP gates may be inserted to route the states. Topic: quantum computing / transpilation / routing