What should a pilot do upon encountering turbulence during an IFR flight?

Reducing airspeed to maneuvering speed and maintaining control is the correct approach for handling turbulence during IFR flight because it allows the pilot to have better control over the aircraft in turbulent conditions. Maneuvering speed is designed to ensure that the aircraft will stall before exceeding its structural limits, protecting it from potential damage due to abrupt changes in wind velocity.

By lowering airspeed, the pilot can make the aircraft less susceptible to the effects of turbulence, making it easier to manage and maintain stability. This is particularly important in low visibility or instrument conditions where precise control is essential.

The other choices do not address the immediate need for control and stability in turbulence. Increasing altitude could potentially lead to encountering more turbulence or may not be feasible depending on air traffic and conditions. Turning back to the departure airport can be impractical and does not guarantee avoiding turbulence, while taking a scenic route does not prioritize the safety and control needed in such situations.