The answer is 1 astronomical unit
        
             
        
        
        
Answer:
I think b 
Explanation:
I think b I am not so sure
 
        
                    
             
        
        
        
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.