When you are applying the pulse oximeter sensor to a patient's finger, he asks you what this device is for. Your response would be:

A) "It provides us with the most accurate measure of your heart rate."
B) "It measures the amount of oxygen being carried by your blood cells."
C) "It tells us how well your heart is pumping blood."
D) "It allows us to monitor your blood pressure and respiratory status."

B) "It measures the amount of oxygen being carried by your blood cells."