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
Function of primary dentition is/are: 
Select and explain. 
A. Formation of clear speech and chewing., B. Provide lip support, cheek support and smile., C. Development and alveolar bone and provide space for secondary dentition., D. All of the above.
D: All of the above.
Answer: D: All of the above. 
Explanation: None