The sinuses are most developed in which demographic?

The sinuses are fully developed in adults, which is why this demographic is the correct answer. In the process of growth and development, the sinuses start to form in early childhood but continue to grow and develop into adolescence and early adulthood.

By the time individuals reach adulthood, the sinuses achieve their maximum size and functional significance. This development is crucial as it allows for adequate ventilation and drainage, helping to prevent issues such as sinusitis and other respiratory problems. While children and teens have developing sinus structures, they do not possess the same level of maturity or size as those found in adults.

In elderly individuals, although the sinuses are still present, they might undergo changes such as thinning of the sinus walls or potential atrophy due to aging. This can sometimes lead to chronic sinus conditions, but the physical development is most robust in adults.