Correct Answer: C
Explanation:
The Hydra's body is a hollow tube consisting of two layers of cells separated by an unstructured gelatinous layer. The outer, clear layer of cells is called the epidermis or ectoderm, and generates the nematocysts. The inner layer is called the endoderm or gastrodermis, and produces the enzymes which digest the Hydra's food. The separating layer is called the mesoglea. It is a gel of various secretions and proteins, containing loose cells not organised into any kind of tissue.