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'.

[EX Q]: Problem: a crow leaves its nest , and flies back and forth from its nest to a nearby ditch to gather worms . the distance between the nest and the ditch is 100 meters . in one and a half hours , the crow manages to bring worms to its nest 15 times . what is the speed of the crow in kilometers per hour ? 
Options: a ) 1 , b ) 2 , c ) 3 , d ) 5 , e ) 7
[EX A]: d

[EX Q]: Problem: convert 500 miles to km ? 
Options: a ) 600 km , b ) 700 km , c ) 800 km , d ) 900 km , e ) 1000 km
[EX A]: c

[EX Q]: Problem: in what time will two trains cross each other completely , which are running on the same parallel lines in opposite directions , each train running with a speed of 60 kmph being 130 m and 120 m in length respectively ? 
Options: a ) 6.9 sec , b ) 7.1 sec , c ) 7.2 sec , d ) 7.4 sec , e ) 7.5 sec
[EX A]:
e