What type of turbulence results in rhythmic bumpiness without significant changes in altitude?

The correct choice highlights a type of turbulence described as "chop," which is characterized by a series of brief, irregular disturbances in the airflow that creates a rhythmic bumpiness within the aircraft. This type of turbulence does not lead to significant altitude changes, making it typically less severe from a passenger experience perspective. Pilots often report "chop" when experiencing sudden, short-lived fluctuations in airspeed or attitude that do not involve pronounced vertical movements.

In contrast, light turbulence involves minor, momentary changes that can be felt but do not significantly affect the flight's altitude. Severe turbulence is marked by abrupt changes in altitude and attitude, making it a more intense experience. Extreme turbulence presents unpredictable, violent movements that can pose serious challenges to the control of the aircraft and the safety of everyone on board. By understanding these distinctions, it's clear why "chop" is cited as the most fitting term for turbulence that induces rhythmic bumpiness without major altitude changes.