【单选题】

The nurse is caring for a client with adult respiratory distress syndrome (ARDS). What is the most likely laboratory finding in the early stages of this disease
A．Increased carboxyhemoglobin.

B．Decreased partial pressure of arterial oxygen (PaO₂).
C．Increased partial pressure of arterial carbon dioxide (PaCO₂).
D．Decreased bicarbonate (
).