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
Which antibiotic acts by inhibiting protein synthesis: 
Select and explain. 
A. Cefotetan, B. Doxycycline, C. Ciprofloxacin, D. Oxacillin
B: Doxycycline
Answer: B: Doxycycline 
Explanation: Doxycycline is a tetracycline that act by inhibiting protein synthesis.
Cefotetan and oxacillin are β-lactam antibiotics that act by inhibiting cell wall synthesis.
Ciprofloxacin is a fluoroquinolone that acts by inhibiting DNA gyrase.