Regarding Pulse Oximetry, Which of the Following Statements Is INCORRECT

Regarding pulse oximetry, which of the following statements is INCORRECT:

A) Pulse oximeters measure the percentage of oxygen dissolved in a sample of plasma by measuring the difference between the amount of red and infra-red light absorption through the vascular bed
B) Modern pulse oximeters have the ability to measure carboxyhaemoglobin and methaemoglobin levels as well as oxygen saturations
C) Anaemic patients can have a normal pulse oximetry reading despite being hypoxic
D) If left in place for extended periods of time pulse oximeter probes can cause pressure areas to develop on the skin, therefore when continuous pulse oximetry is required the probe position should be regularly changed