Fish breathes through
A. Gills
B. Lungs
C. Stomata
D. Skin

Hint: Breathing is the process of exchange of air between the external environment and respiratory organs. In the human body, lungs are the respiratory organs. It takes the Oxygen gas from the environment and releases carbon dioxide to the environment.


Complete step by step answer:
Fishes are aquatic animals. Fishes are also known as water animals. They cannot survive out of water. In most water bodies, fishes are abundant. They can survive in almost every water body. From mountains to hadal depth of deepest ocean fishes are common.
For human fishes are very important resources. Over the entire world fishes are common as a food. In wild fisheries, commercially fishes are hunted. Fish farming is a common occupation for people among the entire world.
The anatomy of fish is very different from humans and mammals. The body of fish is divided into head, tail and trunk. This division is not clearly visible externally. For fishes the respiratory organ is gills.
Correct option is A.

Note:
Lungs are the respiratory organ for humans. Human body has a pair of lungs located in the chest of the human body. Stomata is seen in plants' bodies. Plants respire through the stomata. These are the tiny pores in the plant body. Skin works as a respiratory system for frogs.