What aspect of training involves teaching a horse to respond to commands?

The aspect of training that involves teaching a horse to respond to commands is ground training. During ground training, a horse learns to understand basic cues and commands from the trainer, which is crucial for building a foundation of communication between the horse and the handler. This training often includes leading, stopping, backing up, and responding to vocal commands or body language, helping the horse develop obedience and attentiveness. Ground training establishes trust and respect, making subsequent stages of training, such as riding or more advanced tasks, more effective and safer.

Other choices do not focus primarily on command responsiveness. Trail riding emphasizes the experience of riding in natural settings rather than formal command training. Fitness conditioning centers on improving a horse's physical abilities and stamina, which is important for performance but does not primarily involve command responses. Behavior management focuses on addressing and modifying undesirable behaviors rather than specifically teaching commands.