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: Pathology
Which is the characteristic feature of apoptosis: 
Select and explain. 
A. Nuclear Pyknosis., B. Cellular shrinkage., C. Chromatin clumping., D. Intact cell membrane.
A: Nuclear Pyknosis.
Answer: A: Nuclear Pyknosis. 
Explanation: The most characteristic feature is the nuclear pyknosis. 
Other 

Cellular shrinkage 
Chromatin clumping 
Intact cell membrane 
Cytoplasmic eosinophilia