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: Dental
Electronic instrument used to measure gingival crevicular fluid is 
Select and explain. 
A. Pericheck, B. Periotemp, C. Perioscan, D. Peiotron
D: Peiotron
Answer: D: Peiotron 
Explanation: None