Which of the following systems is responsible for the production of hormones?

The gastrointestinal system primarily focuses on the digestion and absorption of food rather than hormone production. While it does produce some hormones, such as gastrin, its main function is to break down food and process nutrients, making it inadequate as the primary hormonal system compared to the endocrine system.

The lymphatic system is primarily involved in immune responses and the transport of lymph, a fluid that contains infection-fighting white blood cells. It does not have a role in hormone production; instead, it helps in fluid balance and the body's defense mechanisms, which are distinct from hormonal regulation.

The reproductive system is primarily concerned with the production of gametes and the regulation of sexual functions and reproduction. Although it produces hormones such as estrogen and testosterone, it is not the sole system for hormone production, as this function is primarily associated with the broader endocrine system.