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 piece of work in 10 days . b alone can finish it in 20 days . in how many days can a alone finish the work ? 
Options: a ) 20 , b ) 10 , c ) 15 , d ) 5 , e ) 7

A: a
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Q: Problem: raja complete a journey in 10 hours . he travels first half of the journey at the rate of 21 km / hr and second half at the rate of 24 km / hr . find the total journey in km . 
Options: a ) 200 km , b ) 250 km , c ) 224 km , d ) 255 km , e ) 260 km

A: c
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Q: Problem: a train running at the speed of 60 km / hr crosses a pole in 15 seconds . find the length of the train ? 
Options: a ) 250 meter , b ) 876 meter , c ) 167 meter , d ) 719 meter , e ) 169 meter

A:
a
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