This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Disorders of Gastrointestinal System Including Diarrhea, Subject name: Pediatrics
Which of the following is the earliest indicator of pathological gastroesophageal reflux in infants (GERD)? 
Select and explain. 
A. Respiratory symptoms, B. Postprandial regurgitation, C. Upper GI bleed, D. Stricture esophagus
A: Respiratory symptoms
Answer: A: Respiratory symptoms 
Explanation: * Presence of respiratory symptoms point towards pathological GERD * Stricture esophagus and upper GI bleeding are complications due to severe GERD.