The phylum Echinodermata , which contains about 6000 species, gets its name from the Greek, literally meaning "spiny skin." Many echinoderms actually do have "spiny" skin, but others do not. This phylum exists exclusively in the sea, and cannot be found on land or in fresh water.
Answer:
Because of their brightness, how big they are, and how many their are
Explanation:
The answer is:
<u><em>A) Methane</em></u>
because if u picked anything else the reaction would not happen
It has less dense region and it is almost 3 dimensional.
