Task: Question Answering
Input (English): Problem: if 20 men can build a water fountain 56 metres long in 42 days , what length of a similar water fountain can be built by 35 men in 3 days ? 
Options: a ) 3 m , b ) 4 m , c ) 7 m , d ) 9 m , e ) 10 m
Output (English): c