Answer:
a) continue to move at 30 mph
Step-by-step explanation:
As per Newton's First law we know that if object is at rest then it will continue to be in the same state until and unless some external unbalanced force will act upon it
So here we know that
so we can say
then we have
so here we can say that momentum of the system will remain conserve if there is no force on the system
so correct answer will be
a) continue to move at 30 mph