Answer:
Option B, It insulates the fish from the cold air above
Step-by-step explanation:
Water bodies in cold climatic regions have frozen ice at their top. Basically, this ice (frozen water) entraps air pockets inside it which acts like an insulator and prevent the aquatic plants and animals from the extreme cold climate. Thus, ice on the surface of any water body protects the species beneath the ice layer from extreme cold climatic conditions. For example Michigan lakes and ponds get freeze during cold climatic condition.
Option B is correct