Which of the following justifies the need for an already-certified engineer to continue to take classes?
 A. federal regulations are likely to be legislated, so an already-certified engineer needs to become informed.
 B. New developments in sustainability are likely to occur, so an already-certified engineer needs to keep knowledge current.
 C. New engineering certification is required, so an already-certified engineer needs to maintain this licensing.
 D. New local regulations are likely to be legislated, so an already-certified engineer needs to become informed.