Which of the following is located from the rider's waist to the knee and includes the rider's seat and inner thigh?

The base of support refers to the area of contact between the rider and the horse. Specifically, it encompasses the rider's seat and inner thigh, as well as the area from the waist to the knee. This concept is fundamental in riding, as a stable base of support enables the rider to maintain balance and effective communication with the horse.

In riding, the connection between the rider and the horse creates a solid foundation that is crucial for effective movement and aids. The inner thigh and seat are essential points of contact that help the rider stay centered and aligned, which in turn contributes to better control and performance. A well-established base of support leads to improved balance, allowing the rider to influence the horse's movements effectively.

In contrast, the center of gravity refers to the point where the total weight of a body is concentrated, and it can shift depending on the rider's position. The point of balance relates to the horse's center, not the rider, and foot placement refers to where the rider’s feet rest and is important for overall stability but does not specifically describe the area in question.