This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Social and Language Milestones, Subject name: Pediatrics
When does a child begin to wave bye bye? 
Select and explain. 
A. 6 months, B. 9 months, C. 12 months, D. 15 months
B: 9 months
Answer: B: 9 months 
Explanation: A child begins to wave bye bye at the age of 9 months. Impoant milestones at 9 months: Standing with suppo Immature pincer grasp Waves bye bye Speaks bi- syllables like mama, papa, without meaning Bi- syllables babbling CAUTION : TIMING FOR USUAL APPEARANCE OF REFLEX IS NOT SAME AS TIMING FOR LABELLING IT AS RED FLAG SIGN bye bye : appears at 9 months red flag : if bye-bye not present at 12 months Red flag sign means the upper limit for age at which reflex if not present - is abnormal