Certain species of aquatic organisms are particularly sensitive to environmental changes. Scientists often monitor the behavior, population size, and overall health of these so-called indicator species in order to evaluate the water quality in an ecosystem.
Biological indicator species are important to water systems because
OA. they are used to control water quality by filtering out pollutants in an ecosystem.
ОВ.
they become healthier as water quality degrades and can replace weaker species.
OC. they provide an early warning sign of degrading water quality in an ecosystem.
OD. they can convert harmful pollutants into helpful nutrients in an ecosystem.

b.

supercell thunderstorms are perhaps the most violent of all thunderstorm types, and are capable of producing damaging winds, large hail, and weak-to-violent tornadoes

transformative rocks are the stones that emerge from the transformation of existing rock composes in a procedure called changeability, implies changing of structures. transformative rocks are shaped from alternate shakes that are changing a result of warmth or weight connected. one of this model is the earth developments that making rocks profoundly cover or crushed which will make the stones warmed and put under awesome weight. they are not softening but rather the minerals they are containing are changed synthetically that will shape transformative rocks. now and again different rocks are shaped when the others are near some liquid magma and getting warmed.