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: in a city where all streets run east - to - west , all avenues run north - to - south , and all intersections are right angles as shown below , jenn needs to walk from the corner of 1 st street and 1 st avenue to the corner of 6 th street and 3 rd avenue . if her friend amanda is sitting on a bench on 4 th street halfway between 1 st and 2 nd avenues , and jenn chooses her path randomly from any route that will allow her to walk exactly 7 blocks to her destination , what is the probability that jenn will walk down 4 th st . past amanda ? 
Options: a ) 1 / 42 , b ) 1 / 21 , c ) 1 / 7 , d ) 1 / 3 , e ) 1 / 2
Example Output: c

Example Input: Problem: two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 2.9 km and 1.6 km respectively . the time taken by the slower train to cross the faster train in seconds is ? 
Options: a ) 99 , b ) 277 , c ) 48 , d ) 96 , e ) 108
Example Output: e

Example Input: Problem: with both inlets open , a water tank will be filled with water in 36 minutes . the first inlet alone would fill the tank in 2 hours . if in every minutes the second inlet admits 50 cubic meters of water than the first , what is the capacity of the tank ? 
Options: a ) 9,000 , b ) 4,500 , c ) 1,750 , d ) 1,000 , e ) 2,000
Example Output:
b