The first one is the correct answer, I think
A subordinate clause must be combined with an independent clause to end to be a complete sentence
I would go with D for the first one and B for the second one.
It has no mass! Matter is something that CANNOT! have two things at the same spot at the same time. Say you are sitting in a desk at school, no matter where someone else sits, (by you, on top of you, on the desk) they are still not taking up the same space as you are. Sound though, can travel everywhere making it difficult for it to take up only one spot at a time. :)
