What Is the Primary Regulator of the Magnitude of Ventilation

What is the primary regulator of the magnitude of ventilation in normal circumstances?

A) H⁺ concentration of the brain extracellular fluid, which is monitored by central chemoreceptors
B) P_O2 of the arterial blood, which is monitored by central chemoreceptors
C) P_O2 of the arterial blood, which is monitored by peripheral chemoreceptors
D) P_CO2 of the arterial blood, which is monitored by central chemoreceptors