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: Radiology
Contrasts used in USG – 
Select and explain. 
A. Urograffin, B. Ultragraffin, C. Sonavist, D. Conray
C: Sonavist
Answer: C: Sonavist 
Explanation: None