When a marine fish was taken from the ocean and put in a tank of fresh water, it died after a short period because? 

A.

the tank was too small compared to the large ocean

B.

the body cells of the fish swelled and burst as a result of the hypotonic fresh water

C.

the body cells of the fish shrank as their sap was hypertonic to the freshwater

D.

there was no food in the tank, so the fish starved

Correct answer is B

Saltwater fish can't survive in freshwater because their bodies are highly concentrated of salt solution (too much for freshwater). The water would flow into their body until all their cells accumulate so much water that they bloat and die eventually.