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
The maximum carbon content of steel used in dentistry is: 
Select and explain. 
A. 19%, B. 2%, C. 1.70%, D. 4%
C: 1.70%
Answer: C: 1.70% 
Explanation: Carbon steels can be described simply as iron-carbon binary alloys that contain less than 2.1% of carbon by weight.
Composition (percent by weight) of three types of stainless steel by crystal structure of iron