What is the main function of the endocrine system in animals?
A) Coordination
B) Combination
C) Regulatory
D) None of the above

Hint: The system may be a messenger system comprising feedback loops of the hormones released by internal glands of an organism directly into the cardiovascular system regulating distant target organs.

Complete answer:
The function of endocrine glands in animals is to manage chemical coordination. These glands secrete chemicals called hormones.
Coordination the method of controlling and regulating the activities of body metabolism by the system of a nervosum and therefore the system. For instance, the pituitary secretes the Thyroid Stimulating Hormone (TSH) upon the command of the hypothalamus which is a neural part. The TSH regulates the activity of the thyroid to secrete the thyroxine which has an impact on the digestion, respiration and excretion.
The glands of the system are:
- Hypothalamus.
- Pineal Gland.
- Pituitary Gland.
- Thyroid.
- Parathyroid.
- Thymus.
- Adrenal.
- Pancreas.
The hormones created and released by the glands in your body's system control nearly all the processes in your body. These chemicals help coordinate your body's functions, from metabolism to growth and development, emotions, mood, sexual function and even sleep.

Hence, the choice A is the correct answer.

Note:
Hormones are secreted from the glands, they're specific therefore each hormone causes a response in a specific organ or group of cells, instead of in the entire body. Exocrine hormones are secreted via a duct into the blood and typically affect a foreign organ or tissue.