Task: Question Answering
Input (English): Problem: a car traveling at a certain constant speed takes 15 seconds longer to travel 1 kilometer than it would take to travel 1 kilometer at 48 kilometers per hour . at what speed , in kilometers per hour , is the car traveling ? 
Options: a ) 39 , b ) 40 , c ) 41 , d ) 42 , e ) 43
Output (English): b