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 is characteristic of supragingival plaque and not of subgingival plaque in humans? 
Select and explain. 
A. Motile bacteria are predominant, B. Spirochetes are evident microscopically, C. Gram negative bacteria are predominant, D. Bacterial composition is altered by dietary sugar composition
D: Bacterial composition is altered by dietary sugar composition
Answer: D: Bacterial composition is altered by dietary sugar composition 
Explanation: None