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: Microbiology
Which of the following organisms does NOT react with gram's stain? 
Select and explain. 
A. Actinomyces israeli, B. Candida albicans, C. Mycobacterium tuberculosis, D. Streptococcus mutans
C: Mycobacterium tuberculosis
Answer: C: Mycobacterium tuberculosis 
Explanation: None