Which list must a horse not be on to be eligible to race?

For a horse to be eligible to race, it must not be on any list that indicates it is unable or unfit to compete. Being on the starting gate list would imply the horse has been approved and is ready to start a race, while being on the paddock list generally indicates that it is scheduled to race. The veterinarian list is particularly crucial, as it includes horses that are considered unfit or unsound for racing, usually due to health or injury concerns.

If a horse is on the veterinarian list, it clearly cannot race because it has been flagged for medical reasons. Therefore, a horse must not be on any of these lists to ensure its eligibility to participate in a race. This highlights the importance of horse health and safety protocols, ensuring that only fit animals are allowed to compete, thus making the correct answer all of the above.