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
Bone not present at bih- 
Select and explain. 
A. Malleus, B. Incus, C. Stapes, D. Petrous temporal
D: Petrous temporal
Answer: D: Petrous temporal 
Explanation: D i.e. Petrous temporal