In the lower order of invertebrate animals,how does the respiration process take place?

Given below are four matchings of an animal and its kind of respiratory organ:
$1.$ Silver fish - trachea
$2.$ Scorpion - book lung
$3.$ Sea squirt - pharyngeal gills
$4.$ Dolphin - skin
Choose the correct option.

Which of the following modes of respiration always continues in a frog?

Skin of man cannot act as a respiratory organ because

Match List-$I$ with List-$II$:

List-$I$	List-$II$
$A$. Molluscs	$I$. Pulmonary respiration only
$B$. Reptiles	$II$. Branchial respiration
$C$. Adult amphibians	$III$. Cellular respiration
$D$. Amoeba	$IV$. Pulmonary and Cutaneous respiration

Choose the correct answer from the options given below:

Fishes have . . . . . . for respiration.