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
All of the following are helpful for diagnosis of Medullary Ca thyroid except- 
Select and explain. 
A. Spindle cell stroma with few follicles, B. Amyloid deposition, C. Calcitonin in stroma, D. Histological mitochondria is essential for diagnosis
D: Histological mitochondria is essential for diagnosis
Answer: D: Histological mitochondria is essential for diagnosis 
Explanation: None