Answer:
I believe it is A, but I could be wrong.
Explanation:
I think this, because when it says, "Other, less useful, versions of the genetic code were eliminated gradually throughout the course of evolution", I think it referencing to the fact that all animals and etc, are made up of common codes, and how over time, through evolution, certain codes were eliminated, because creatures were evolving.
Mostly fungal species are multicellular but yeast is unicellular
It would be called a biome, like a tundra or a desert.
Notchochord, morphology, chordates
The answer is: Abscisic acid.
