Task: Question Answering
Input (English): Problem: a whale goes on a feeding frenzy that lasts for 9 hours . for the first hour he catches and eats x kilos of plankton . in every hour after the first , it consumes 3 kilos of plankton more than it consumed in the previous hour . if by the end of the frenzy the whale will have consumed a whopping accumulated total 450 kilos of plankton , how many kilos did he consume on the sixth hour ? 
Options: a ) 38 , b ) 47 , c ) 50 , d ) 53 , e ) 62
Output (English): d