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: Unknown
Which of the following is not a direct route for transmission of communicable diseases? 
Select and explain. 
A. Skin contact, B. Vertical, C. Droplet nuclei, D. Soil contact
C: Droplet nuclei
Answer: C: Droplet nuclei 
Explanation: Ref. Foundations of Community medicine. Page. 393