How do the nervous, muscular and skeletal system work together to help us move?

The nervous system controls various organs of the body directly. The skeletal system makes up the framework of the body and allows us to move when our muscles contract. It stores minerals (e.g. calcium, phosphorous) and releases them into the body when they are needed.

phylogenetic tree is the tree of life or evolution tree. it shows the different branches of evolution. the sequence goes like tissues - coelom - backbone - endoskeleton - segmentation

chert is a sedimentary rock composed of microcrystalline or cryptocrystalline silica. with this little bit of information, you can come to the conclusion that your answer is c.  

explanation: