PLEASE PLEADE HELP!?!?

The universe could be considered an isolated system because (2 points) Select one:
a. many people think that no energy or matter exists outside the universe.

b. energy and matter are created in the universe and flow freely into and out of the universe.

c. energy is created outside the universe and matter is created within the universe.

d. energy is created in the universe and matter is transferred out of the universe.