A client visits an urgent care center while on vacation in Colorado. The client reports difficulty breathing since arriving. Which factor most likely explains the client's dyspnea?
a. The client is experiencing a sickle cell crisis.
b.The high altitudes prevent oxygen from binding to hemoglobin.
c.The client has consumed large amounts of caffeinated coffee.
d.The client has underlying chronic obstructive pulmonary disease (COPD).