What is a characteristic feature of the adrenal gland?

The adrenal gland is primarily known for its role in hormone production, and one of its key hormones is cortisol. This hormone is crucial for various bodily functions, including supporting metabolism, regulating the immune response, and helping the body respond to stress.

Cortisol is part of the glucocorticoids group of hormones produced by the adrenal cortex, which is the outer layer of the adrenal gland. The production of hormones like cortisol directly relates to the gland's function and significance within the endocrine system.

In contrast, the other options reference functions or features that do not pertain to the adrenal glands. For instance, insulin production is associated with the pancreas, calcium regulation is largely the function of the parathyroid glands and other structures, and the adrenal glands are typically located on top of the kidneys rather than beneath the sternum.