Which of the following are included in the stomach massage exercises?

The stomach massage exercises in Stott Pilates are designed to target the core muscles and enhance spinal mobility. The correct answer includes "Prep, Round back, Straight back," which represents the three key positions utilized in the stomach massage series.

The "Prep" phase serves to establish the initial position and align the body correctly to ensure proper engagement of the core musculature. Following this, the "Round back" position focuses on flexion of the spine, which emphasizes the contraction of the abdominal muscles while promoting a rounded posture. Lastly, the "Straight back" position allows for an extension of the spine, engaging different muscle groups and providing a counterbalance to the flexion that occurred in the previous phase. This sequence effectively trains the muscles of the abdomen while also promoting spinal control and strength.

The other choices present different combinations of movements that do not accurately represent the structure of the stomach massage exercises. The absence of the specific terms associated with the stomach massage series makes them less suitable for this particular question.