Which type of mount is characterized by jumping from the board to a back handspring?

The described mount, which involves jumping from the board into a back handspring, is best represented by the roundoff onto a board followed by the back handspring. This combination demonstrates a transition that incorporates both the entry from the board and seamlessly leading into the back handspring, which is essential for judges to assess the athlete's technique and fluidity in connecting the elements.

Engaging in a roundoff before the back handspring showcases the gymnast's ability to generate power and momentum, which is critical in achieving height and proper form during the back handspring. The execution of such a mount is indicative of advanced skill and coordination, aligning with the expectations at level 10 competitions.

In contrast, the other types of mounts mentioned do not directly involve the specified sequence of jumping onto the board followed by a back handspring, making them unsuitable in this context. Hence, the correct choice emphasizes the specific mechanics and flow characteristic of that particular mount type.