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
Investment material used for high fusing base metal partial dentures 
Select and explain. 
A. Gypsum bonded., B. Phosphate bonded., C. Silica bonded., D. All of the above.
C: Silica bonded.
Answer: C: Silica bonded. 
Explanation: Silica bonded
• Silica is the binder which may be derived from ethyl silicate or silica gel
• Used for high fusing base metal partial denture alloys
• In addition to setting shrinkage "green shrinkage" occurs due to loss of alcohol and water from the gel.
• The investment can be heated upto 1200°C