Final answer:
Endocrine glands function at the organ level of biological organization, secreting hormones directly into the bloodstream to regulate body processes and maintain homeostasis. Each gland is an organ in itself, part of the larger endocrine system.
Step-by-step explanation:
The endocrine glands are part of a complex network known as the endocrine system, which operates at multiple levels of biological organization. When considering the hierarchy within the biological organization of the endocrine glands, they function at the organ level. Each endocrine gland is an organ that secretes hormones directly into the bloodstream to regulate various body functions and maintain homeostasis.
The endocrine system includes several major glands such as the pituitary, thyroid, parathyroid, adrenal, and pineal glands. It also comprises organs and tissues with secondary endocrine functions like the pancreas, which has a role in digestion alongside its insulin and glucagon hormone production. The hierarchy within biological systems progresses from larger, more inclusive levels to smaller, more specific levels. It starts with the organism at the top and moves down through the organ system, organ, tissue, cell, and finally to the molecule.
Therefore, the correct answer to the question about the level of organization endocrine glands are involved in is c) Organ level.