It is water pollution, since you are polluting the river.
Hope I helped!
The answer is they go parasite seeing. It is Paris sightseeing.This question or joke is commonly and popularly used in punchline algebra books that can be cracked by interpreting and decoding English expressions into algebraic expressions and setting up the equations.
The process is called condensation
I do believe it would be the last one in which it describes how how the other species would decline in population size and migrate
