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: two trains a and b are 125 m and 150 m long and are moving at one another at 54 km / hr and 36 km / hr respectively . arun is sitting on coach b 1 of train a . calculate the time taken by arun to completely cross train b . 
Options: a ) 10 s , b ) 11 s , c ) 4 s , d ) 8 s , e ) 12 s
Example Output: b

Example Input: Problem: find the area of trapezium whose parallel sides are 28 cm and 18 cm long , and the distance between them is 15 cm . 
Options: a ) 227 , b ) 299 , c ) 345 , d ) 161 , e ) 212
Example Output: c

Example Input: Problem: a can do a piece of work in 5 days and b can do it in 7 days how long will they both work together to complete the work ? 
Options: a ) 6 / 11 , b ) 8 / 11 , c ) 7 / 12 , d ) 9 / 12 , e ) 10 / 11
Example Output:
d