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
Lingual bar is used in conditions where: 
Select and explain. 
A. Lingual sulcus is deep, B. Lingual sulcus is shallow, C. When splinting of adjacent teeth is require, D. When abutment teeth have poor bony support
A: Lingual sulcus is deep
Answer: A: Lingual sulcus is deep 
Explanation: None