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
Localised shrinkage porosity is seen when there is 
Select and explain. 
A. Thin sprue, B. Investment heated strongly, C. Inadequate air discharge, D. Low casting pressure
A: Thin sprue
Answer: A: Thin sprue 
Explanation: None