The correct option is C Mesoderm
Humans are triploblastic animals. Triploblastic organisms are made up of 3 germ layers - ectoderm, endoderm and mesoderm. The primary sex organs develop from the mesoderm.
The central nervous system is of ectodermal origin.
The digestive system is of endodermal origin.
Mesoglea is an undifferentiated tissue layer found between the endoderm and ectoderm in diploblastic animals such as Cnidaria and Coelenterates.