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 man rows his boat 75 km downstream and 45 km upstream , taking 2 1 / 2 hours each time . find the speed of the stream ? 
Options: a ) 6 , b ) 7 , c ) 5 , d ) 8 , e ) 9

A: a
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Q: Problem: if a train , travelling at a speed of 360 kmph , crosses a pole in 5 sec , then the length of train is ? 
Options: a ) 381 m , b ) 112 m , c ) 500 m , d ) 125 m , e ) 433 m

A: c
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Q: Problem: how many bricks each measuring 22 cm x 10.25 cm x 8 cm , will be needed to build a wall 9 m x 7 m x 10.5 m 
Options: a ) 5600 , b ) 3066 , c ) 3055 , d ) 7200 , e ) none of these

A:
b
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