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
Apical collar signifies: 
Select and explain. 
A. Retentive form, B. Resistance form, C. Both 1 & 2, D. None
A: Retentive form
Answer: A: Retentive form 
Explanation: ΑPICΑL COLLAR = Retentive form (usually nearly 2 mm of parallel walls at apical region) 
Keyword is TUG BACK.