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: dan can do a job alone in 15 hours . annie , working alone , can do the same job in just 10 hours . if dan works alone for 3 hours and then stops , how many hours will it take annie , working alone , to complete the job ? 
Options: a ) 2 , b ) 4 , c ) 6 , d ) 8 , e ) 10

A: d
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Q: Problem: in what time will a railway train 110 m long moving at the rate of 36 kmph pass a telegraph post on its way ? 
Options: a ) 6 sec , b ) 7 sec , c ) 8 sec , d ) 11 sec , e ) 2 sec

A: d
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Q: Problem: a swimmer can swim in still water at 4 km / h . if the speed of the water current is 2 km / h , how many hours will the swimmer take to swim against the current for 3 km ? 
Options: a ) 1.5 , b ) 1.75 , c ) 2.0 , d ) 2.25 , e ) 2.5

A:
a
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