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
5th cusp is usually not seen in: 
Select and explain. 
A. Mandibular 1st molar, B. Mandibular 2nd molar, C. Mandibular 3rd molar, D. Maxillary 1st molar
B: Mandibular 2nd molar
Answer: B: Mandibular 2nd molar 
Explanation: None