Closed system - Is defined when a particular quantity of matter is under study. Consist of fixed amount of mass.

What does that mean? a matter cannot enter and exit a close system right? So does that mean in a close system there’s a little bit amount of matter in it?

Ibelieve it is answer b. provides military aid.

Asmall closed hole formed in an outwash plain or moraine. forms when a  glacier retreats then remains stationary. 

Europe needs to build a trump-like wall that will spread across europe making it impossible for migrants to cross they need to spread pig guts all over this wall so the muslims will never consider crossing into europe..you might be asking "can't they just fly over with planes? " well yes they can so we will install thaad missile protections system to shoot down any aircraft that violates europe's air fourth would be to start a fourth reich in germany.. last but not least.. make europe great again!

100% tortilla. it is the only possible answer