Answer:
The correct answer is option b. "PCO₂ and H₂ of cerebral spinal fluid".
Step-by-step explanation:
The central respiratory chemoreceptors (CRCs) are cells involved in respiratory feedback and are located in the ventrolateral surface of medulla oblongata. CRCs respond to changes in the PCO₂ and H₂ of cerebral spinal fluid, contributing to the stimulation of breathing mainly by performing two processes: hypercapnia or metabolic acidosis.