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: Pharmacology
Long acting insulin preparations are frequently administered by: 
Select and explain. 
A. Oral route, B. Intramuscular route, C. Intradermal route, D. Subcutaneous route
D: Subcutaneous route
Answer: D: Subcutaneous route 
Explanation: None