Peripheral chemoreceptors in the aortic bodies and central chemoreceptors respond to changes in which of the following physiologic parameters?

Peripheral chemoreceptors in the aortic bodies and central chemoreceptors respond to changes in which of the following physiologic parameters? a. Both H+ and PCO2 b. H+ alone c. H+, PCO2, and PO2 d. PO2 alone e. PCO2 alone