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. :)
Its d) I had this question couple of days ago
Some questions I have regarding this is
How does cell phones disconnect us from reality?
What are some Health effects that come with long term use of a cell phone?
What are some Environmental Hazards when a cell phone is thrown out?
Does Blue light effect the brain in any way and if it does is there and impacts on how we communicate with people?
I think 5. should be the 3rd option, but 5 and 6 look good. I am not sure about 7, sorry >.<
2nd Option: He writes about the pure innocence of nature.