Detailed Instructions: 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: two trains are moving in opposite directions @ 100 kmph and 120 kmph . their length are 500 m and 700 m . the time taken by the slower train to cross faster train in second is ?
Options: a ) 15 sec , b ) 18.3 sec , c ) 19.6 sec , d ) 20.4 sec , e ) 22.5 sec
A:
c