This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Trauma, Subject name: Surgery
Which of the following structure is fixed during reimplantation of an amputated digit 
Select and explain. 
A. Bone, B. Aery, C. Vein, D. Nerve
A: Bone
Answer: A: Bone 
Explanation: .