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'.

[Q]: Problem: an seller earns an income of re 1 on the first day of his business . on every subsequent day , he earns an income which is just thrice of that made on the previous day . on the 20 th day of business , he earns an income of : 
Options: a ) 29 , b ) 57 , c ) 35 , d ) 20 , e ) 30
[A]: b


[Q]: Problem: noelle walks from point a to point b at an average speed of 6 kilometers per hour . at what speed , in kilometers per hour , must noelle walk from point b to point a so that her average speed for the entire trip is 7 kilometers per hour ? 
Options: a ) 6.75 , b ) 7 , c ) 7.25 , d ) 7.5 , e ) 8.4
[A]: e


[Q]: Problem: find the area of a cuboid of length 4 cm , breadth 6 cm . and height 5 cm . 
Options: ['a ) 120 cm cube', 'b ) 110 cm cube', 'c ) 220 cm cube', 'd ) 430 cm cube', 'e ) 480 cm cube']
[A]:
a