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
[{'content': 'Due to high viscosity of viscous gel etchants, areas are left where etchant does not flow. This is known as: \nSelect and explain. \nA. Skipping effect, B. Dripping effect, C. Trapping effect, D. None of the above', 'role': 'user'}, {'content': 'Answer: A \nExplanation: None', 'role': 'assistant'}]