The correct option is D The patient has been inhaling polluted air containing usually high carbon monoxide content
If the blood analysis of a patient reveals an unsually high quantity of carboxyhaemoglobin, it can be concluded that the patient has been inhaling polluted air containing high carbon monoxide content.
Carbon monoxide forms a stable compound with haemoglobin called carboxyhaemoglobin, since affinity of haemoglobin for carbon monoxide is 200 times greater than its affinity for oxygen. In this form, haemoglobin does not carry oxygen, eventually resulting in death due to lack of oxygen in tissues.
Hb(Haemoglobin)+CO⟶HbCO(Carboxyhaemoglobin)