Given below are four matchings of an animal and its kind of respiratory organ :
A. Silver fish – trachea
B. Scorpion – book lung
C. Sea squirt – pharyngeal gills
D. Dolphin – skin
The correct matchings are : -

A. Silverfish (Lepisma) is an insect; insects breathe through a network of tracheae. Correct.
B. Scorpion (an arachnid) breathes through book lungs. Correct.
C. Sea squirt (Herdmania, a urochordate) uses its pharyngeal gill slits for respiration and filter feeding. Correct.
D. Dolphin is an aquatic mammal; it breathes air through lungs (coming to the surface through its blowhole), not through the skin. Incorrect.
So the correct matchings are A, B and C.