Match List I with List II

List I		List II
A	Pleurobrachia	I	Mollusca
B	Radula	II	Ctenophora
C	Stomochord	III	Osteichthyes
D	Air bladder	IV	Hemichordata

Choose the correct answer from the options given below:

To match the biological structures/organisms in List I with their corresponding phylum or characteristic features in List II, we can analyze each item step-by-step:

A. Pleurobrachia: Pleurobrachia is a genus of marine invertebrates commonly known as sea gooseberries. They belong to the phylum Ctenophora (comb jellies), characterized by comb plates used for locomotion. Therefore, A matches with II.

B. Radula: The radula is a rasping, tongue-like organ equipped with chitinous teeth, used for scraping or cutting food before it enters the esophagus. It is a unique characteristic feature of the phylum Mollusca. Therefore, B matches with I.

C. Stomochord: The stomochord is a flexible, hollow tube found in hemichordates. It arises as an outpocketing from the roof of the embryonic gut and extends forward into the proboscis. It is a defining feature of the phylum Hemichordata. Therefore, C matches with IV.

D. Air bladder: The air bladder (or swim bladder) is a gas-filled organ that helps bony fish regulate their buoyancy, allowing them to maintain their depth without wasting energy in swimming. This structure is a characteristic feature of class Osteichthyes (bony fishes). Therefore, D matches with III.

Combining these individual matches, we get:
A - II
B - I
C - IV
D - III

Thus, the correct option representing this matching is A-II, B-I, C-IV, D-III.