This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory, Subject name: Medicine
Which of the following blood gas results is most likely in a patient with hyperventilation caused by anxiety? 
Select and explain. 
A. increased PCO2, B. decreased PO2, C. decreased pH, D. decreased PCO2
D: decreased PCO2
Answer: D: decreased PCO2 
Explanation: The behavioral respiratory control system of the brain drives the hyperventilation, which leads to decreased PCO2 and increased pH. If alkalemia is present with the hypocarbia, symptoms can be quite significant. They include dizziness, visual impairment, syncope, and seizures secondary to cerebral vasoconstriction; paresthesia's, carpopedal spasm, and tetany (secondary to decreased free serum calcium); muscle weakness (secondary to hypophosphatemia); and cardiac arrhythmias (secondary to alkalemia).