The endocrine system is composed of organs and glands. It controls and coordinate the body, including reproduction, growth, mood, etc. The glands and organs involved acts upon all of those factors hrough hormones, which are produced and secreted by the endocrine system. The system responsible for sensing the environment is the Nervous System, therefore b) is incorrect. Ransoming materials throughout the body is one of the functions of the blood, which is not an organ or a gland of the Nervous System, therefore a) is also incorrect. The Digestive System is responsible for breaking down food into smaller parts, therefore c) is wrong as well. As we said that the Endocrine System secretes hormones, the correct answer is d) to secrete hormones.