In which part of the body is glucagon primarily produced?

Glucagon is primarily produced in the pancreas, specifically by the alpha cells located in the islets of Langerhans. This hormone plays a critical role in glucose metabolism by promoting the release of glucose into the bloodstream, especially during fasting or low blood sugar situations. When blood glucose levels drop, glucagon triggers the liver to convert stored glycogen into glucose and release it into the bloodstream, thus increasing blood sugar levels.

The other options pertain to different functions in the body; for example, the liver is involved in glucose storage and release, but it is not the site of glucagon production. The adrenal glands are responsible for producing hormones like cortisol and adrenaline, while the thyroid gland primarily produces hormones that regulate metabolism and growth. Hence, none of these other structures produce glucagon.