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: a boat covers a certain distance downstream in 1 hour , while it comes back in 1 ½ hours . if the speed of the stream be 3 kmph , what is the speed of the boat in still water ? 
Options: a ) 12 kmph , b ) 13 kmph , c ) 14 kmph , d ) 15 kmph , e ) none
[A]: d


[Q]: Problem: a and b together can do a work in 4 days . if a alone can do it in 20 days . in how many days can b alone do it ? 
Options: a ) 11 , b ) 5 , c ) 6 , d ) 8 , e ) 25
[A]: b


[Q]: Problem: a biker covered half the distance between two towns in 2 hr 30 min . after that he increased his speed by 2 km / hr . he covered the second half of the distance in 2 hr 20 min . find the distance between the two towns and the initial speed of the biker . 
Options: a ) 140 , b ) 120 , c ) 130 , d ) 150 , e ) 160
[A]:
a