Answer:
The correct hypothesis would be - "if a water body contains a high amount of heavy metals such as chromium and lead then the death of the fishes will increase because lead and chromium affect the aquatic environment and gills of fishes."
Step-by-step explanation:
Heavy metal like chromium in a high concentration can affect the gills of the fishes, it is seen in fishes that swim at the point of disposal of metals at thewater surface harm their gills. In high concentration, it becomes toxic for the fishes.
Lead also causes a negative impact on the aquatic ecosystem if accumulated in a high amount in the aquatic environment that leads to the death of the fishes.