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 of 25 carriages , each of 60 meters length , when an engine also of 60 meters length is running at a speed of 60 kmph . in what time will the train cross a bridge 1.0 km long ? 
Options: a ) 2.5 , b ) 3 , c ) 5 , d ) 7 , e ) 9
Example Output: a

Example Input: Problem: two cyclist start on a circular track from a given point but in opposite direction with speeds of 7 m / s and 8 m / s . if the circumference of the circle is 630 meters , after what time will they meet at the starting point ? 
Options: a ) 20 sec , b ) 15 sec , c ) 42 sec , d ) 50 sec , e ) 1 min
Example Output: c

Example Input: Problem: a car going at 20 miles per hour set out on an 80 - mile trip at 9 : 00 a . m . exactly 10 minutes later , a second car left from the same place and followed the same route . how fast , in miles per hour , was the second car going if it caught up with the first car at 10 : 30 a . m . ? 
Options: a ) 40 , b ) 50 , c ) 53 , d ) 55 , e ) 60
Example Output:
a