What is the temperature requirement of sand, for manufacturing?

• A. Below 40¬¨¬®‚Äö√†√ªC
• B. Below 50¬¨¬®‚Äö√†√ªC
• C. Below 60¬¨¬®‚Äö√†√ªC
• D. Below 70¬¨¬®‚Äö√†√ªC