Which tissue are the first to develop?

epithelium

The formation of the first embryonic epithelium is associated with the development of both complex cell-cell adhesion machinery and also cellular and the sub-cellular polarization. This first epithelial supracellular architecture subsequently leads to the first mesenchymal supracellular architecture: the mesoderm.

Explanation:

it's     c       this is a cell (b) with a nucleus (c) containing dna (a). the dna is organized into chromosomes (d). a section of the chromosome that codes for a trait is called a gene (e).

organ system-an organ system is a group of organs that work together to perform one or more functions. each does a particular job in the body, and is made up of certain tissues.