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'.
Input: Problem: two trains are moving at 50 kmph and 70 kmph in opposite directions . their lengths are 170 m and 100 m respectively . the time they will take to pass each other completely is ?
Options: a ) 3 sec , b ) 8 sec , c ) 9 sec , d ) 5 sec , e ) 7 sec
Output:
b