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: the radius of a circular wheel is 1.75 m , how many revolutions will it make in traveling 1 km ? 
Options: ['a ) 1000', 'b ) 2788', 'c ) 2677', 'd ) 2899', 'e ) 2771']
Example Output: a

Example Input: Problem: a cistern 8 m long and 6 m wide contains water up to a breadth of 1 m 85 cm . find the total area of the wet surface . 
Options: a ) 102 m sqaure , b ) 100 m sqaure , c ) 152 m sqaure , d ) 164 m sqaure , e ) none of these
Example Output: b

Example Input: Problem: a pump can fill a tank with water in 6 hours . because of a leak , it took 12 hours to fill the tank . the leak can drain all the water in ? 
Options: a ) 12 hr , b ) 11 hr , c ) 13 hr , d ) 14 hr , e ) 16 hr
Example Output:
a