Final answer:
The body's communication systems include the hormonal and nervous systems, which maintain homeostasis through the release of hormones and electrical/chemical signaling. The central nervous system, part of the nervous system, is composed of the brain and spinal cord.
Step-by-step explanation:
The communication systems of the body include the hormonal and nervous systems. These two systems are responsible for maintaining homeostasis, which means they help the body to maintain a stable internal environment. The endocrine system is composed of glands that secrete hormones into the bloodstream, regulating various bodily functions. These hormones reach target cells and elicit specific responses essential for the body's adaptation and balance. Examples include the adrenal glands that produce stress hormones and the thyroid gland, which regulates metabolism. On the other hand, the nervous system employs electrical and chemical signaling to rapidly communicate information between neurons and target cells. The central nervous system, part of the larger nervous system, consists of the brain and spinal cord. Additionally, the nervous system includes both somatic and autonomic divisions, with the autonomic nervous system further divided into sympathetic and parasympathetic nervous systems, controlling involuntary bodily functions like heart rate and digestion. Therefore, the correct answer is d) both a and b, as both the hormonal and nervous systems are involved in body communication. In contrast, the excretory system (c) is not primarily responsible for communication.