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
Phagocytosis of TB bacilli does not occur because of - 
Select and explain. 
A. Wax D, B. Muramyl dipeptide, C. Cord factor, D. Peritrichate Cilia
C: Cord factor
Answer: C: Cord factor 
Explanation: Virulent strains of tubercle bacilli form microscopic "serpentine cord" in which acid fast bacilli are arranged in parallel chains, cord formation is correlated with virulence. A "cord factor" has been extracted from virulent bacilli with petroleum ether. It inhibits migration of leukocytes, causes chronic granulomas, and can serve as an immunologic "adjuvant"