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'.

Problem: a rower can row 5 km / h in still water . when the river is running at 2 km / h , it takes the rower 1 hour to row to big rock and back . how many kilometers is it to big rock ? 
Options: a ) 1.5 , b ) 1.8 , c ) 2.1 , d ) 2.4 , e ) 2.7
c

Problem: it will take 16 days for mary to complete a certain task alone . she worked for 8 days before she was joined by her sister . both of them completed the remaining task in 2 and half days . if her sister had joined her when she started the task , how many days would it have taken ? 
Options: a ) 6 , b ) 8 , c ) 2 , d ) 5 , e ) 4
d

Problem: in what time will a train 250 metres long cross an electric pole , if its speed be 162 km / hr ? 
Options: a ) 4 sec , b ) 5 sec , c ) 5.55 sec , d ) 6.55 sec , e ) 4.55 sec

c