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
Tanerella forsythus is a periodontal pathogen 
Select and explain. 
A. Gram positive, non-obligate, B. Non-pleomorphic rod, C. Non - obligate anaerobe, D. Non-motile, spindle shaped organism
D: Non-motile, spindle shaped organism
Answer: D: Non-motile, spindle shaped organism 
Explanation: None