Which of the following factors relates to the mare's reproductive potential?

Each of the factors listed contributes significantly to a mare's reproductive potential. The age of the mare is crucial, as younger mares typically have higher fertility rates compared to older mares who may experience a decline in reproductive health.

The health status of the mare is also vital; a mare that is healthy, free from diseases, and in optimum physical condition is more likely to conceive and carry a foal to term successfully.

Genetic background plays a role as well, as it can influence the mare's predisposition to certain reproductive traits and issues. Mares from lines known for strong reproductive capabilities are more likely to pass these traits on to their offspring.

Considering these points, it is clear that all listed factors—age, health status, and genetic background—interact to determine the overall reproductive potential of a mare. This interconnectedness highlights the importance of evaluating each of these aspects when assessing a mare for breeding purposes.