Above what temperature is the phenomenon of creep important in steel?

• A. 200 ¬¨¬®‚Äö√†√ªC
• B. 500 ¬¨¬®‚Äö√†√ªC
• C. 300 ¬¨¬®‚Äö√†√ªC
• D. 600 ¬¨¬®‚Äö√†√ªC