The primary form of cortisol in the plasma is that which is:

Ans. D. Bound to corticosteroid-binding globulin (CBG)Cortisol, like other steroid hormones, is carried in the blood largely bound to carrier proteins, although a small percentage exists free in solution. The majority of cortisol is bound to a specific carrier protein, corticosteroid-binding globulin (CBG), while smaller amounts are bound nonspecifically to albumin. Few, if any, cortisol receptors would be expected in the plasma and transthyretin binds primarily thyroxine.