Who is recognized for introducing the concept of vertical take-off and landing (VTOL)?

The designers of the Harrier Jump Jet are recognized for introducing and popularizing the concept of vertical take-off and landing (VTOL). The Harrier, which emerged in the 1960s, is notable for its unique ability to take off and land vertically, thanks to its vectored thrust engines. This innovation allowed the aircraft to be used in varied environments, including small or improvised airfields, making it a significant advancement in military aviation. The success and operational use of the Harrier set the stage for further developments in VTOL technology and inspired subsequent designs in both military and civilian aviation.

Other choices, while involve advancements in aviation, do not specifically and singularly relate to the development and implementation of VTOL technology in the same pioneering way as the Harrier team's contributions.