What is the best description of a closed system?

a system in which matter and energy are not exchanged with the surroundings
a system in which both matter and energy are exchanged freely between the system and the surroundings
a system in which energy can enter or leave the system but matter cannot
a system in which matter can enter or leave the system but energy cannot

How is the city of savannah related to the union strategy of a full blockade of confederate ports? a) savannah was the last port needed to be secured in order to totally blockade the coast of georgia. b) savannah was the least significant city in georgia, and the union strategy centered on securing atlanta and capturing the tennessee river. c) savannah was the least significant city in georgia, and the union strategy centered on securing atlanta and capturing the chattahoochee river. d) savannah was the most significant port in georgia, and the union strategy centered on securing bases at savannah and the outlying islands to fully blockade georgia.