B. increase, because the partial pressure of CO2 in the blood will decrease.
Explanation:
The presence of carbon dioxide gas in blood imparts H+ ions due to its reaction with H2O and thereby, lowers down the blood pH.
When more air reaches alveoli, the rate of gaseous exchange is increased. More of the carbon dioxide is removed from the blood and is released out of the body via exhalation.
Removal of carbon dioxide from blood would increase the pH of the blood since the partial pressure of CO2 in the blood would decrease.
