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
Due to high viscosity of viscous gel etchants, areas are left where etchant does not flow. This is known as: 
Select and explain. 
A. Skipping effect, B. Dripping effect, C. Trapping effect, D. None of the above
A: Skipping effect
Answer: A: Skipping effect 
Explanation: None