Is this a multiple choice question or...??
If not, I'd say, that its simple as scientists can easily decipher which variable caused the situations result. And thats because you may have one manipulated variable to be able to know the responding variable.
The answer is A: Polyploidy is a condition in which an organism acquired more than the normal amount of chromosomes.
Hope this helps.
The best answer to the question that is being given above would be letter A. The most complex level of organization hierarchy that climate change could potentially affect is Earth's Biosphere - which holds every living thing in the planet. This climate change will destroy it more destruction to Mother Nature occurs.