Which of the following are characteristics of mature execution of a basketball jump shot?

The characteristics of mature execution of a basketball jump shot primarily include having the knees slightly flexed, which helps generate power and stability, and ensuring that the shooting hand, elbow, and shoulder are aligned with the target. This alignment is crucial for accuracy and consistency in shooting. A stable base provided by slightly flexed knees allows the shooter to maintain balance and to explode upward effectively when taking the jump shot.

In addition to alignment, maintaining a proper stance with knees flexed helps to improve the overall mechanics of the shot, ensuring that the player's body moves in a coordinated manner. This holistic approach to positioning aids in both the upward motion and the follow-through, which are integral to a successful jump shot.

Other options describe elements that are not typically associated with a mature shooting technique. For example, having feet together may limit balance and power generation, while being airborne during the shot without any part of the feet touching the ground isn't ideal for a stable shot. A flat shooting motion with no follow-through also indicates a lack of proper shooting technique, as follow-through is essential for controlling the trajectory of the ball and ensuring accuracy.