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 of the following series act as the best space
maintainer in a child's mouth? 
Select and explain. 
A. Restored deciduous tooth, B. Acrylic partial denture, C. Distal shoe space maintainer, D. Band and loop space maintainer
A: Restored deciduous tooth
Answer: A: Restored deciduous tooth 
Explanation: None