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: Anatomy
Which of the following attains adult size before bih: 
Select and explain. 
A. Ear ossicles, B. Maxilla, C. Mastoid, D. Mastoid
A: Ear ossicles
Answer: A: Ear ossicles 
Explanation: A i.e. Ear ossiclesAuditory (ear) ossicles attain full adult size at (or before) bihQ. Although mastoid antrum (air sinus) is well developed (& of adult size) at bih, but mastoid process & air cells develop later.