Which is not an echinoderm? a) sea star b) sea urchinc) sand dollard) spider

The wings of insects, birds, and bats evolved independently but carry out similar functions. this is an example of a. analogous structures. b. embryonic structures. c. vestigial structures. d. homologous structures.

This part insulates the reaction chamber from the transfer of heat to or from the surrounding environment

What is the problem in this article? what solution does the article propose?