Fact 1: Hormones are chemical messengers that control many body functions. Fact 2: Hormones are produced and released by the endocrine system . Given the two facts above, which body system releases chemical messengers that control many body functions?

Select from the following.
i. athletes
ii. acetic acid
iii. sweating
iv. Endocrine system
v. heat or cold
vi. Electrical energy
vii. Veins and arteries.
viii. sensory neurons
Answer:
iv.