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
The following are true of Mendelson's syndrome – 
Select and explain. 
A. Critical volume of aspirate is 50 mls, B. Critical pH of gastric aspirate is 1.5, C. Onset of symptoms generally occurs within 30 minutes, D. Steroids have been shown to improve outcome
C: Onset of symptoms generally occurs within 30 minutes
Answer: C: Onset of symptoms generally occurs within 30 minutes 
Explanation: Symptoms of Mendelson's syndrome generally occurs within 30 minutes of aspiration.
Critical pH is 2.5 and critical volume is 25 ml.
Use of corticosteroid is generally not recommended.