Task: Question Answering
Input (English): Problem: two trains are moving in opposite directions at 60 km / hr and 90 km / hr . their lengths are 2.10 km and 1.4 km respectively . the time taken by the slower train to cross the faster train in seconds is ? 
Options: a ) 99 , b ) 277 , c ) 84 , d ) 96 , e ) 22
Output (English): c