The correct option is B Connective tissue
Connective tissue is absent in Hydra.
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.
This is because cnidarians (like Hydra) are diploblastic. This means that the developing organism consists of two layers: the ectoderm and the endoderm. The epidermis is formed from the ectoderm and the gastrodermis is formed from the endoderm.