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
Fiber-optic trans-illumination (FM) method of caries
diagnosis is based on the principle of: 
Select and explain. 
A. When Laser beam falls on carious enamel, it gives a bluish hue., B. A fluorescent dye is taken up by carious dentine which can be viewed easily, C. There	is	a	different index	of	light	transmission	for decayed or sound enamel., D. The conductance of normal and decayed tooth tissue is different.
C: There	is	a	different index	of	light	transmission	for decayed or sound enamel.
Answer: C: There	is	a	different index	of	light	transmission	for decayed or sound enamel. 
Explanation: None