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: Surgery
In patients with breast cancer, chest wall involvement means  involvement of any one of the following structures except: 
Select and explain. 
A. Serratus anterior, B. Pectoralis, C. Intercoastal muscles, D. Rib
B: Pectoralis
Answer: B: Pectoralis 
Explanation: None