In this task, you need to answer the given multiple-choice question on the gain. Gain is the value by which to multiply the input. Classify your answers into 'a', 'b', 'c', 'd', and 'e'.

Problem: a man walking at a rate of 10 km / hr crosses a bridge in 10 minutes . the length of the bridge is ? 
Options: a ) 1521 , b ) 1492 , c ) 1667 , d ) 1254 , e ) 1112
c