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: it will take 16 days for mary to complete a certain task alone . she worked for 8 days before she was joined by her sister . both of them completed the remaining task in 2 and half days . if her sister had joined her when she started the task , how many days would it have taken ? 
Options: a ) 6 , b ) 8 , c ) 2 , d ) 5 , e ) 4
Example Output: d

Example Input: Problem: raja complete a journey in 10 hours . he travels first half of the journey at the rate of 21 km / hr and second half at the rate of 24 km / hr . find the total journey in km . 
Options: a ) 200 km , b ) 250 km , c ) 224 km , d ) 255 km , e ) 260 km
Example Output: c

Example Input: Problem: two parallel sides of a trapezium are 4 cm and 5 cm respectively . the perpendicular distance between the parallel sides is 6 cm . find the area of the trapezium . 
Options: ['a ) 24 cm 2', 'b ) 25 cm 2', 'c ) 26 cm 2', 'd ) 27 cm 2', 'e ) 28 cm 2']
Example Output:
d