What is the name of the offspring produced by breeding a jennet and a stallion?

The offspring produced by breeding a jennet (a female donkey) and a stallion (a male horse) is called a hinny. A hinny is distinct from a mule, which is the result of breeding a mare (female horse) and a jack (male donkey). Hinnies and mules have differing characteristics due to the lineage involved in their genetic makeup.

Understanding the distinction between these terms is essential in animal husbandry and breeding practices. The hinny is generally less common than the mule, and this difference often results in variations in physical traits and behavior between the two types of hybrid animals.

The other options refer to different concepts: a mule is the hybrid offspring of a mare and a jack; a foal is a young horse, typically one that is less than a year old; and a pony refers to a small horse breed rather than a hybrid animal. Each of these terms has its specific definition and does not directly relate to the breeding pair indicated in the question.