The correct answer is option C. secrete chemical messengers that travel in the bloodstream.
Explanation:
Endocrine glands are organ or gland that secrets hormones that are chemical messengers travel through the bloodstream instead of the duct. There are several glands that are part of the endocrine system such as the thyroid gland, pancreas, hypothalamus, and others.
These chemical agents are the travel through the blood and act on the site of action.
Thus, the correct answer is option C. secrete chemical messengers that travel in the bloodstream.
Killer whales are found in all oceans. While they are most abundant in colder waters like Antarctica, Norway, and Alaska, they are also found in tropical and subtropical waters. The most well-studied killer whale populations occur in the eastern North Pacific Ocean.
