This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Radiological anatomy, Subject name: Radiology
What is the structure 'B' marked in lateral chest X-ray below? 
Select and explain. 
A. Major fissure, B. Minor fissure, C. Azygos fissure, D. Transverse fissure
A: Major fissure
Answer: A: Major fissure 
Explanation: None