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
What is the number of layers in greater omentum? 
Select and explain. 
A. 1, B. 2, C. 3, D. 4
D: 4
Answer: D: 4 
Explanation: The greater omentum is folded back on itself and is therefore made up of four layers of closely applied visceral peritoneum, which are separated by variable amounts of adipose tissue. Ref: Gray's anatomy 40th edition, Chapter 69.