question: The world 's largest `` free-at-the-point-of-use '' ambulance service is known as what ?
answer: the London Ambulance Service ( LAS ) NHS Trust
turker_answer: The world 's largest `` free-at-the-point-of-use '' ambulance service is known as the London Ambulance Service ( LAS ) NHS Trust .
rule-based: The world 's largest `` free-at-the-point-of-use '' ambulance service is known as the London Ambulance Service ( LAS ) NHS Trust .