What must a cowboy do to successfully "mark out" in bronc riding?

To successfully "mark out" in bronc riding, a cowboy must have his feet above the horse's shoulders at the moment the horse's feet hit the ground. This is a critical aspect of the bronc riding scoring system, as it demonstrates the rider's control and skill right from the start. Marking out is designed to ensure that the rider is in a proper position when the ride begins, showcasing the importance of both technique and safety.

When a cowboy's feet are positioned correctly, it indicates to the judges that he is prepared for the ride and allows him to better handle the unpredictable movements of the bronc. This technique also helps in maintaining balance and control throughout the ride, which is essential for scoring well.

The focus on positioning at the start is further emphasized in the context of the other choices. Staying on the horse for a complete eight seconds and performing tricks, while important aspects of bronc riding, do not concern the initial requirements for marking out. Using a rope to secure oneself to the saddle is not standard practice in bronc riding and would not be considered a valid technique. Thus, the correct answer highlights the foundational skill necessary for bronc riding competition.