Which two statements are true about a system? a system is a group of objects analyzed as one unit. energy that moves across system boundaries is conserved there's only one way to define the boundaries of a system all systems are made by humans

i think it’s a. this is because if they measured the mass of something with a mass of 150g, then their final answer would have to be approximately 150g. though all of their answers are almost 150, rosa and tran have the closest answers (or the exact answer) to the accurate one.

3. dark matter

empty space could also be a simple vacuum