This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Monitoring in Anesthesia, Subject name: Anaesthesia
All true about interaction of reading of spo2 and methemoglobinaemia, except- 
Select and explain. 
A. MetHb absorbs red and infrared wavelength of light in a 1:1 ratio corresponding, B. Increase in Methb produce an underestimation when spo2 > 70%, C. Increase in Met Hb produce an overestimation when spo2 <70%, D. Does not get affected in Methemoglobinaemia
D: Does not get affected in Methemoglobinaemia
Answer: D: Does not get affected in Methemoglobinaemia 
Explanation: Met Hb absorb red and infrared wavelengths of light in a 1:1 ratio corresponding to an SpO2 of approximately 85%. Therefore, increases in Met Hb produce an underestimation when SpO2> 70% and an overestimation when SpO2 <70%.