Final answer:
a. Physical Education. The subject related to the demonstrated knowledge of principles and stages of motor development is Physical Education.
Step-by-step explanation:
The subject related to the demonstrated knowledge of principles and stages of motor development is Physical Education. Physical Education focuses on the development of motor skills and physical fitness through various activities and exercises. It involves learning about the principles of motor development, such as the stages of motor development, how motor skills are acquired, and the factors that influence motor development.
In Physical Education, students study topics like the different stages of motor development in children, the progression of motor skills from infancy to adulthood, and how the development of motor skills impacts overall physical fitness and health. They also learn about the importance of proper exercise technique, safety, and injury prevention when engaging in physical activity.