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'.

Input: Consider Input: Problem: pipes a and b can fill a tank in 3 and 4 hours . pipe c can empty it in 4 hours . if all pipes are opened together , then the tank will be filled in ? 
Options: a ) 3 hr , b ) 1 / 2 hr , c ) 1 hr , d ) 9 / 7 hr , e ) 5 / 3 hr

Output: a


Input: Consider Input: Problem: a student travels from his house to school at 10 km / hr and reaches school 1 hour late . the next day he travels 12 km / hr and reaches school 1 hour early . what is the distance between his house and the school ? 
Options: a ) 100 , b ) 105 , c ) 110 , d ) 115 , e ) 120

Output: e


Input: Consider Input: Problem: a and b complete a work in 4 days . a alone can do it in 8 days . if both together can do the work in how many days ? 
Options: a ) 3.75 days , b ) 3.99 days , c ) 2.67 days , d ) 2.98 days , e ) 2.44 days


Output: c