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: Dental
Oral habit that occurs during intrauterine stage is: 
Select and explain. 
A. Atypical swallowing, B. Tongue thrusting, C. Thumb sucking, D. Lip sucking
C: Thumb sucking
Answer: C: Thumb sucking 
Explanation: Thumb sucking habit  is seen in the oral stage of development and is seen at 29 week of intrauterine life and may disappear during normal growth between the ages of 1 and 3.5 years.