The correct answer to this question is option 4: Thymosin. The thymus gland is responsible for producing several hormones, including thymosin. Thymosin plays a major role in the development and maturation of T cells, which are a type of white blood cell that plays a crucial role in the immune response. Thymosin helps in the production and differentiation of T cells, ensuring that they are able to recognize and respond to foreign pathogens effectively. It also aids in the formation of the immune system in early life. This hormone is specific to the thymus gland and is not produced by other glands in the body. Therefore, Thymosin is the correct hormone produced by the thymus gland.