The correct option is C Hexacanth
The six-hooked embryo of Taenia is called hexacanth. It has a pair of penetration glands and is surrounded by two hexacanth membranes. The hexacanth embryo, hexacanth membranes, basement membrane, embryophore and the eggshell or chorionic membrane together is known as onchosphere. The gravid proglottids which pass out from the host body contain embryos in onchosphere stage. So, option C is correct.