In this task, you need to answer the given multiple-choice question on the physics. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Example Input: Problem: a train is 485 meter long is running at a speed of 45 km / hour . in what time will it pass a bridge of 140 meter length 
Options: a ) 20 seconds , b ) 30 seconds , c ) 40 seconds , d ) 50 seconds , e ) none of these
Example Output: d

Example Input: Problem: a train 250 m long is running at a speed of 45 km / hr . in what time will it pass a bridge 150 m long ? 
Options: a ) 45 sec , b ) 42 sec , c ) 32 sec , d ) 48 sec , e ) 25 sec
Example Output: c

Example Input: Problem: a certain car uses 12 gallons of gasoline in traveling 300 miles . in order for the car to travel the same distance using 10 gallons of gasoline , by how many miles per gallon must the car ’ s gas mileage be increased ? 
Options: a ) 2 , b ) 4 , c ) 5 , d ) 8 , e ) 10
Example Output:
c