Task: Question Answering
Input (English): Problem: a man traveled a total distance of 1800 km . he traveled one - third of the whole trip by plane and the distance traveled by train is two - thirds of the distance traveled by bus . if he traveled by train , plane and bus , how many kilometers did he travel by bus ? 
Options: a ) 660 , b ) 680 , c ) 720 , d ) 760 , e ) 800
Output (English): c