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
Invasive squamous cell carcinoma is differentiated from carcinoma in situ by: 
Select and explain. 
A. Penetration of basement membrane, B. Number of mitotic figures, C. Increased in size of cell, D. Nuclear pleomorphism
A: Penetration of basement membrane
Answer: A: Penetration of basement membrane 
Explanation: None