Final answer:
A decrease in blood pH below normal tends to stimulate increased respirations and stimulate a compensatory increase in blood hydrogen ion concentration through the respiratory system.
Step-by-step explanation:
A decrease in blood pH below normal tends to stimulate increased respirations (option A) and stimulate a compensatory increase in blood hydrogen ion concentration through the respiratory system (option C).
When blood pH decreases, it indicates an increase in acidity, which is known as acidosis. The respiratory system responds to acidosis by increasing the rate and depth of respiration, which helps remove carbon dioxide (CO2) from the blood. The removal of CO2 reduces the level of carbonic acid, thus increasing blood pH and compensating for the acidosis.