B) Carotid and aortic bodies are peripheral chemoreceptors that are stimulated primarily by hypocapnia is correct.
 

Key Concept/Objective: To understand the key concepts of the physiology of ventilatory control.

Ventilation is a critical function for eliminating carbon dioxide and acquiring oxygen. The control system for ventilation not only optimizes gas exchange but also serves a role in acid-base homeostasis, speech, deglutition, defecation, and postural adjustments. Inhalation and exhalation begin with the discharge properties of putative pacemaker neuronal groups located in the medulla. This neural network is embedded in a system of adjacent medullary neurons, pontine neurons, and regions such as the NTS that receive neural impulses through lung inflation, lung deflation, blood pressure, and other afferent systems. The intensity of the activity of medullary neurons is affected by chemoreceptors. The peripheral chemoreceptors -- the carotid and aortic bodies -- are highly vascular collections of specialized sensory cells. The carotid bodies are located bilaterally at the bifurcations of the common carotid arteries; the aortic bodies are situated anterior and posterior to the arch of the aorta and left main pulmonary artery. The peripheral chemoreceptors are stimulated primarily by a low arterial oxygen tension (P_aO₂), although hypercapnia, acidemia, and, possibly, hyperthermia may influence the gain of the response to hypoxemia. Impulses travel from the carotid and aortic bodies to the NTS via sensory ganglia and the afferent nerves that follow along the ninth and 10th cranial nerves, respectively. Increases in P_aCO₂ stimulate cells on the ventral medullary surface, primarily by lowering the pH of the medullary extracellular fluid. Specialized sensory cells (mechanoreceptors) located in the upper airway, chest wall, and lung detect mechanical deformation and temperature changes resulting from inhalation and exhalation.