Question: The Boeing 377 Stratocruiser was a large long-range airliner developed from the C-97 Stratofreighter military transport, itself a derivative of which four-engine propeller-driven heavy bomber designed by Boeing, which was flown primarily by the United States during World War II and the Korean War?
Sentence (from "Petlyakov Pe-8"): Produced in limited numbers, it was used to bomb Berlin in August 1941.
Relevant evidence: No