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'.

[EX Q]: Problem: calculate the circumference of a circular field whose radius is 8 centimeters . 
Options: a ) 17 π cm , b ) 18 π cm , c ) 1 π cm , d ) 16 π cm , e ) 6 π cm
[EX A]: d

[EX Q]: Problem: a hiker walked for 3 days . she walked 18 miles on the first day , walking 3 miles per hour . on the second day she walked for one less hour but she walked one mile per hour , faster than on the first day . on the third day 5 miles per hour for 6 hours . how many miles in total did she walk ? 
Options: a ) 68 , b ) 44 , c ) 58 , d ) 60 , e ) 62
[EX A]: a

[EX Q]: Problem: two pipes a and b can fill a tank in 6 hours and 4 hours respectively . if they are opened on alternate hours and if pipe a is opened first , in how many hours , the tank shall be full ? 
Options: a ) 2 hrs , b ) 4 hrs , c ) 5 hrs , d ) 6 hrs , e ) 7 hrs
[EX A]:
c