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
According to weins modification of the working length determination if bone resorption is there then: 
Select and explain. 
A. Reduce the length by 0.5mm, B. Reduce the length by 1mm, C. Reduce the length by 1.5mm., D. Reduce the length by 2mm.
C: Reduce the length by 1.5mm.
Answer: C: Reduce the length by 1.5mm. 
Explanation: Wein modification of working length determination by radiograph: 
1. Reduce length by 1 mm if NO root + bone resorption 
2. Reduce length by 1.5 mm if bone resorption 
3. Reduce length by 2 mm if both root and bone resorption