Which of the following is a key responsibility of a horse trainer during the training process?

Managing feeding regimens is a key responsibility of a horse trainer during the training process because it directly impacts the health, performance, and overall well-being of the horses. Proper nutrition is crucial for supporting the energy levels, muscle development, and recovery of racehorses. A trainer must carefully plan and monitor what each horse eats, ensuring they receive the right balance of nutrients appropriate for their training intensity and racing needs.

Additionally, a well-structured feeding regimen aids in maintaining optimal body weight and condition, which are vital for peak performance during races. Monitoring individual horses' responses to their diets allows trainers to make necessary adjustments, enhancing their chances of success. A trainer's expertise in nutrition reflects their understanding of the physiological needs of racing horses, making it an essential component of their training responsibilities.

The other options, while relevant to the horse racing industry, do not fall within the primary scope of a trainer’s duties.