Which of the following is a prohibited maneuver concerning spins?

Spins with the landing gear extended are prohibited due to the increased risk of structural damage to the aircraft and the potential for a more severe recovery situation. When the landing gear is down, it can create increased drag and adverse aerodynamic effects during a spin, making recovery more difficult and potentially leading to further complications. The presence of the landing gear can also lead to greater risks of parts failure or loss of control during a spin, as the aircraft's configuration is not optimized for such maneuvers.

The other options, while they might involve challenges, do not carry the same level of risk associated with structural integrity and control effectiveness as attempting spins with the landing gear extended. Spins can still be managed under specific conditions, provided that operational limits are adhered to, but having the gear down significantly alters aerodynamic dynamics in a critical phase of flight.