Question

In fishes, respiration take place by
A. Gills and scales
B. Book lungs
C. Gills, book lungs and fins
D. Gills, accessory organs

Answer 1

Respiration is defined as the process in which carbon dioxide is released out and oxygen is carried inside that is absorbed. Respiration is the essential process for breakdown of food from complex material to the simple ones. It helps to keep the organs of the body in a well-positioned manner.

Complete answer:
Fishes are the group of member vertebrates. In these structures the notochord is replaced by the vertebral column. Fishes are aquatic animals so they have to breathe more and more faster to obtain oxygen as water has less oxygen when compared to the terrestrial environment.
Now let is match from which organs fishes respire:

Gills and scales: gills of the fishes help in the respiration as gills are covered with operculum but scales do not help in the process of respiration. But scales help to prevent fishes from the predators and also helps to reduce friction with water.
Book lungs: these structures are used for respiration but not in the fishes. These are present in arthropods and are a kind of modified book gills. They are seen in scorpions and spiders.
Gills, book lungs and fins:- gills help in respiration in fishes, book lungs helps in respiration in arthropod and fins do not help in respiration rather they act as balancers and brakes and provide lift and also helps in counteract pitching.
Gills, accessory organs:- gills help in respiration, they help to absorb oxygen. There are many accessory organs present in fishes such as dendritic organs present in clarias or cat fish and integument present in eels which helps in respiration.

Our required option is D that is gills, accessory organs.

Note:
Fish when taken out of water die of suffocation due to lack of oxygen. This is because the gill filaments stick together when taken out of water, thereby reducing the surface area. So fishes need water to survive as their gills are only functional in water.