The dependant variable would be the salmon, because they depend on the water and pollution levels to give a result.
I hope this helps you!! :)
You can classify them in what phase they are in: solid, liquid, gas
You can classify them in Sizes
You can classify them by the number of moons they have
You can classify them by distance from the sun
You can classify them all as heliocentric or orbiting/circling around the sun
You can classify them by color
Actually Welcome to the Concept of the Genes.
Basically a Polygenetic trait is controlled by two or more genes.
Examples of human polygenic inheritance are height, skin color, eye color and weight. Polygenes exist in other organisms, as well.
On average, women live longer than men