Answer:
D. in the past few decades, carbon dioxide levels have been falling.
Well usually it takes a couple of weeks and u have to take a test to find out if ur pregnant
I believe the example of an environmental variation in the above question is, A. Marge dyes her hair blue. Variation represents any difference between cells, individual organisms, or groups of organisms of any species caused by either genetic differences or by the effect of environmental factors. Environmental variation is the ability of an organism to alter its phenotype depending on environmental conditions.
