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: Dental
The marrow found in the mandible is: 
Select and explain. 
A. All fatty marrow, B. All red marrow, C. All fibrous marrow, D. A combination of fatty and fibrous marrow
D: A combination of fatty and fibrous marrow
Answer: D: A combination of fatty and fibrous marrow 
Explanation: None