Final answer:
Paracrine substances signal neighboring cells to stabilize and maintain homeostasis, with quick, localized responses.
Step-by-step explanation:
Paracrine substances are important communicators in maintaining homeostasis within the body. The correct answer to the question is b) They signal neighboring cells to maintain stability. Paracrine signals are chemical substances that induce a response in neighboring cells through diffusion through the extracellular matrix. These signals are localized and usually elicit quick responses of a short duration. An example of paracrine signaling is histamine, which is released by immune cells in the bronchial tree and causes the smooth muscles of the bronchi to constrict. Unlike endocrine signals that travel through the bloodstream to reach distant organs, paracrine signals act locally and are quickly degraded or removed, which helps to maintain homeostasis by affecting cells in the immediate vicinity.