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
For calculating drug dosage, which of the following formula is not age-dependent: 
Select and explain. 
A. Young's formula., B. Cushing's rule., C. Cowling's formula., D. Clark's rule.
D: Clark's rule.
Answer: D: Clark's rule. 
Explanation: None