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 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: what is the length of a bridge ( in meters ) , which a train 156 meters long and travelling at 45 km / h can cross in 30 seconds ? 
Options: a ) 203 , b ) 211 , c ) 219 , d ) 227 , e ) 235
[A]: c


[Q]: Problem: in a kilometer race , a beats b by 25 meters or 10 seconds . what time does a take to complete the race ? 
Options: a ) 167 sec , b ) 190 sec , c ) 390 sec , d ) 716 sec , e ) 123 sec
[A]:
c