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: Radiology
Normal level of alveolar crest below the CEJ of the adjacent teeth is: 
Select and explain. 
A. 0.5-1 mm, B. 1-1.5 mm, C. 1.5-2.0 mm, D. 1-2 mm
B: 1-1.5 mm
Answer: B: 1-1.5 mm 
Explanation: ALVEOLAR CREST:
The gingival margin of the alveolar process that extends between the teeth is apparent on radiographs as a radiopaque line—the alveolar crest. The level of this bony crest is considered normal, when it is not more than 1.5 mm from the cementoenamel junction of the adjacent teeth.
Reference: White and Pharoah's Oral Radiology Principles and Interpretation 7th edition page no 133