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 first step in surveying the cast for RPD is: 
Select and explain. 
A. Establishment of guiding plane, B. Establishment of undercuts for retention, C. Establishment of tooth contour for esthetics, D. Establishment of interferences for major connector
A: Establishment of guiding plane
Answer: A: Establishment of guiding plane 
Explanation: None