Which of the following must a bonus at Level 10 include?

A bonus at Level 10 must include both a D skill and an E skill, which is referred to as a D and E bonus. This requirement is essential because it encourages gymnasts to incorporate more difficult elements into their routines, showcasing their advanced technical skills and increasing the level of difficulty of their performances.

At Level 10, which is the highest level in the Junior Olympic program, the expectation is for gymnasts to demonstrate a high level of proficiency with more challenging elements. The "D" and "E" ratings are indicative of this difficulty, and including both in a routine is necessary for achieving a bonus, which can help with the overall score.

In contrast, bonuses involving just one of the skills or including only the CV (Connection Value) bonus do not meet the Level 10 requirements, as they do not reflect the higher difficulty level that is expected at this level. Thus, the inclusion of both a D and an E skill is crucial for receiving the bonus and maximizing the scoring potential of the routine.