This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Anaesthesia
Mendelson syndrome is due to – a) Aspiration pneumonitisb) Chemical pneumonitisc) Oesophagitisd) Oesophageal spasm 
Select and explain. 
A. ac, B. ab, C. ad, D. bc
B: ab
Answer: B: ab 
Explanation: Mendelson's syndrome is aspiration pneumonitis caused by aspiration of gastric fluid into the lung.
Aspiration pneumonitis is a chemical pneumonitis due to chemical reaction produced by gastric acid.