Which of these is considered a gonadal hormone?

Testosterone is classified as a gonadal hormone because it is produced by the gonads, specifically the testes in males and, to a lesser extent, the ovaries in females. Gonadal hormones are responsible for the development and regulation of the reproductive systems, as well as secondary sexual characteristics. Testosterone plays a crucial role in male sexual development, including sperm production, and contributes to muscle growth and body hair distribution.

In contrast, thyroid hormone is produced in the thyroid gland and regulates metabolism; insulin is produced by the pancreas and is central to glucose metabolism; cortisol is a steroid hormone produced by the adrenal glands and is involved in the stress response and metabolism. None of these hormones originate from the gonads, hence they do not qualify as gonadal hormones.