Which mode would you switch to if rapid altitude changes were required?

Switching to vertical speed mode is the correct choice when rapid altitude changes are required because this mode allows the pilot to directly control the rate of ascent or descent. In vertical speed mode, the aircraft can be set to climb or descend at a specified rate, enabling the pilot to make significant altitude adjustments quickly and efficiently. This is particularly useful in situations where immediate altitude changes are necessary, such as avoiding obstacles or responding to sudden changes in the environment.

Other modes, such as altitude hold mode, would maintain the aircraft at a specific altitude rather than allow for rapid changes, and thus would not be suitable for situations requiring quick altitude adjustments. Heading select mode primarily manages lateral navigation and does not directly affect altitude. Turbulence mode generally pertains to maintaining stability during turbulent conditions rather than facilitating rapid altitude changes.