Select the option which shows the correct combination of an organism and its feature. 

Balanoglossus is a hemichordate. In hemichordates, body is divided into a proboscis, collar and a long trunk. Echinus is an echinoderm. Special excretory organs are absent in echinoderms. Dentalium is a mollusc. Molluscs are unsegmented. Fertilisation is mostly internal in arthropods (e.g., Bombyx), except a few aquatic forms.