The derived characteristic of protostome development is found in which of the following phyla?
a. sponges
b. roundworms
c. cnidarians
d. echinoderms

B. Roundworms. 

The Protostome organisms are subclustered into three main groups, moreover nematoda or roundworms belongs to the Ecdysozoa group.

Roundworms are organisms that are diverse and almost in clustered to many other ecosystems and environment. 

These Protostome  includes mollusks, annelids, and arthropods

b. the carbon cycle ensures living things have a source of hydrogen

i was thinking 4.0 v hope this