Final answer:
Pilates instructors are responsible for teaching Pilates exercises.
Step-by-step explanation:
Pilates instructors are responsible for teaching Pilates exercises, which fall within their scope of practice. They are not qualified to prescribe medication (a), as that is the role of medical doctors. Physical therapy techniques (b) also do not fall within the scope of practice of Pilates instructors, as physical therapy requires specialized training and certification. Creating customized diets (c) is typically the role of a nutritionist or dietitian, not a Pilates instructor.