The correct answer to the Youth Show & Go quiz is only the Single Leg Show & Go is Legal in Youth 3. The Show & Go to Liberty is not allowed in Youth or younger divisions. When the video ends, the single based liberty being shown is held at extended level, not just immediately passing through extended level, which is not allowed because of the rule stating:
Single based or assisted single based EXTENDED stunts are not allowed in Tiny, Mini and Youth divisions.
The Single Leg Show & Go video is allowed because of a clarification added to the rule above. The clarification says:
Clarification: Single based or assisted single based stunts may immediately pass through an extended position.
The clarification allows the stunt to pass through extended position as long as it’s not held in the extended position, such as what’s done in a typical show and go. Although the clarification was added for the 2017-18 season, the rule was previously enforced as if the clarification already existed. This means there isn’t a noticeable change in the rule, the wording was just updated to match the way it was enforced.
This clarification makes it clear that a stunt like a full up to prep, that passes through being an extended single based stunt on the way up, continues to be allowed in Youth Level 3.
The explanation is based on the 2017-18 version of the cheer rules dated August 30, 2017.