What was the key innovation of the Boeing 747?

The significance of the Boeing 747 lies heavily in its status as the first wide-body airliner. This design revolutionized commercial aviation by allowing for a larger fuselage, which enabled it to accommodate more passengers and cargo. The wide-body configuration made it possible to add dual aisles and increased seating capacity, reducing the cost per seat for airlines and simultaneously making air travel more accessible to the public. The Boeing 747's innovative design set a new standard for passenger comfort, with features that were not common in narrower aircraft.

Although the other options highlight important features or characteristics of the Boeing 747, such as its size and advancements in technology like turbofan engines and in-flight entertainment, the introduction of the wide-body design was crucial in reshaping the airline industry and increasing efficiency in air travel.