Which gland is not found on the lips or sex organs?

The correct choice is that the gland not found on the lips or sex organs is the thyroid gland.

The thyroid gland is an endocrine gland located in the neck that produces hormones responsible for regulating metabolism, growth, and development. It is not associated with exocrine functions, which involve glands that release their secretions through ducts to external surfaces or into body cavities.

In contrast, the apocrine and eccrine glands are types of sweat glands found in various locations on the body, including the sex organs. Apocrine glands are primarily located in areas such as armpits and the genital region, while eccrine glands are more widely distributed across the body, including on the palms, soles, and forehead.

The pineal gland, which is also an endocrine gland, is located in the brain and plays a role in regulating sleep patterns through the secretion of melatonin. It is not related to the skin or mucous membranes, such as those found on the lips or in sexual organs.

Thus, the thyroid gland is the one that does not have any involvement or presence in those areas, making it the correct choice.