The nerve that stimulates the diaphragm is:

A. Tachypnea refers to rapid breathing. While it can affect the balance of gases in the blood, it typically leads to decreased CO₂ levels, which would actually reduce blood acidity (increase pH).
B. Dyspnea refers to difficult or labored breathing. It can be associated with respiratory distress, but it does not directly cause significant changes in blood acidity.
C. Hyperpnea is characterized by increased depth and rate of breathing, often to meet metabolic demands, like during exercise. This typically decreases CO₂ levels, which can lead to a reduction in blood acidity (increase in pH).
D. Apnea, which is the cessation of breathing, would lead to a buildup of CO₂ in the blood because the body is not expelling it through normal respiration. This increase in CO₂ would combine with water to form carbonic acid, thereby lowering blood pH and increasing acidity.

A. Carotid artery and aorta contain the carotid bodies and aortic bodies, which are peripheral chemoreceptors. These structures detect changes in blood oxygen, carbon dioxide, and pH levels, sending signals to the respiratory centers to adjust breathing accordingly.
B. The cerebellum and pons are parts of the brain involved in motor control and respiratory rhythm, respectively, but do not contain peripheral chemoreceptors.
C. The coronary sinus and alveoli are not involved in detecting chemical changes in the blood for breathing regulation. The coronary sinus drains blood from the heart muscle, and the alveoli are sites of gas exchange, not chemoreception.
D. The brachiocephalic vein and superior vena cava are large veins that return deoxygenated blood to the heart but do not house chemoreceptors involved in respiratory regulation.