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: how long does a train 90 m long traveling at 60 kmph takes to cross a bridge of 170 m in length ? 
Options: a ) sec , b ) sec , c ) sec , d ) sec , e ) sec
Example Output: d

Example Input: Problem: a train is 360 meter long is running at a speed of 30 km / hour . in what time will it pass a bridge of 140 meter length ? 
Options: a ) 87 , b ) 69 , c ) 60 , d ) 72 , e ) 21
Example Output: c

Example Input: Problem: how many bricks , each measuring 25 cm x 11 cm x 6 cm , will be needed to build a wall of 2 m x 3 m x 2 cm ? 
Options: a ) 5600 , b ) 6000 , c ) 73 , d ) 7200 , e ) 8600
Example Output:
c