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 does not form a boundary of the triangle of auscultation: 
Select and explain. 
A. Serratus anterior, B. Latissimusdorsi, C. Trapezius, D. Scapula
A: Serratus anterior
Answer: A: Serratus anterior 
Explanation: Serratus anterior