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: convert 500 miles to km ?
Options: a ) 600 km , b ) 700 km , c ) 800 km , d ) 900 km , e ) 1000 km
[A]: c

[Q]: Problem: the length of the bridge , which a train 475 metres long and travelling at 90 km / hr can cross in 30 seconds , is :
Options: a ) 200 m , b ) 225 m , c ) 245 m , d ) 250 m , e ) 275 m
[A]:
e