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
Traces of which of the following antibiotics can be found in the gingival fluid after administration: 
Select and explain. 
A. Tetracycline, B. Lincomycin, C. Clindamycin, D. Penicillin G
A: Tetracycline
Answer: A: Tetracycline 
Explanation: None