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
Which of the following is not used as an antiflux? 
Select and explain. 
A. Graphite, B. Boric acid, C. Iron oxide, D. Calcium carbonate with alcohol
B: Boric acid
Answer: B: Boric acid 
Explanation: The flow of the flux and hence the solder can be limited by the use of an antiflux, which should be applied to the surface before the flux is applied.
Zinc oxides in alcohol, rouge (iron oxide) in chloroform, whiting (calcium carbonate) in alcohol and graphite suspension are the commonly used antifluxes.
Key comment :
The boric acid/borax acts as flux.