Which of the following has a central gastro-vascular cavity with a single opening, mouth on hypostome?

Hydra (a cnidarian) has a central gastro-vascular cavity with a single opening, mouth on hypostome. Scypha has a spongocoel which opens out by an osculum. Taenia lacks a body cavity and a mouth. Locusta is an insect. Its body cavity is haemocoel. Its alimentary canal has two openings – mouth and anus.