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
Tripoding of cast is used for 
Select and explain. 
A. Blocking out undercuts, B. Recording position on surveyor, C. Locating guiding plane, D. Determining path of insertion
B: Recording position on surveyor
Answer: B: Recording position on surveyor 
Explanation: Some method of recording the relation of the cast to the vertical arm of the surveyor must be used so that it may be returned to the surveyor for future reference, especially during mouth preparation. The same applies to the need for returning any working cast to the surveyor for shaping wax patterns, trimming blockout on the master cast, or locating clasp arms in relation to undercut areas. This is done by tripoding.