This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
The primary reason for the use of drug combination in the treatment of tuberculosis is 
Select and explain. 
A. Ensure patient compliance with the drug regimen, B. Enhance activity against metabolically inactive mycobacteria, C. Delay or prevent emergency of resistance, D. Provide prophylaxis against other bacterial infection
C: Delay or prevent emergency of resistance
Answer: C: Delay or prevent emergency of resistance 
Explanation: Ref-KDT 6/e p745 The bacteria that cause tuberculosis (TB) can develop resistance to the antimicrobial drugs used to cure the disease. Multidrug-resistant TB (MDR-TB) is TB that does not respond to at least isoniazid and rifampicin, the 2 most powerful anti-TB drugs. ... In some cases even more severe drug-resistant TB may develop.