Which one of the following phyla is correctly matched with its two general characteristics? 

• Arthropoda - Body divided into head, thorax and abdomen and respiration by tracheae.

• Chordata - Notochord at some stage and separate anal and urinary openings to the outside

• Echinodermata - Pentamerous radial symmetry and mostly internal fertilisation

• Mollusca - Normally oviparous and development

A.

Arthropoda - Body divided into head, thorax and abdomen and respiration by tracheae.

Arthropoda is the largest phylum of the animal kingdom. The body of an arthropod is divisible into head, thorax and abdomen. Head and thorax often fused to form a cephalothorax. The respiration takes place by general body surface, gills tracheae or book lungs.
Molluscs are dioecious or monoecious, one or more gonads with conducts, opening into renal ducts or to the exterior. The fertilisation is external or internal, development direct or through free larval forms. 
Echinoderma has pentamerous radial symmetry derived from an original bilateral symmetry. The fertilization is external, development indirect through free - swimming larvals forms. 
Chordates are sharply distinguished from non-chordates by the presence of notochord, dorsal tubular central nervous system and phayngeal gills slits.