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: Pharmacology
Cross-resistance can be one way or two way, one-way resistance can be seen in: 
Select and explain. 
A. Neomycin and streptomycin, B. Tetracycline and doxycycline, C. Sulphadiazine and sulphadoxine, D. None of the above
A: Neomycin and streptomycin
Answer: A: Neomycin and streptomycin 
Explanation: Organisms that develop resistance to an antimicrobial agent may also show resistance to other  chemically related AMAs. The cross-resistance among AMAs could either be one-way or two-way.  Cross-resistance among tetracyclines and sulphonamides is usually ‘two-way’.