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
Which type of prefabricated post preparation system in mandibular molar is preferred? 
Select and explain. 
A. Tapered, screwed in, B. Parallel, screwed in, C. Tapered, passively cemented, D. Parallel, partially cemented
D: Parallel, partially cemented
Answer: D: Parallel, partially cemented 
Explanation: None