A boy walks down the sidewalk with a trash bag while two other boys follow him .
It is impossible that a boy is chasing after the bag while his two friends try to catch up .
It is impossible that a boy is chasing after the bag while his two friends try to catch up .
It is likely that a boy is chasing after the bag while his two friends try to catch up .
A boy is chasing after the bag while his two friends try to catch up .