Which position in a codon shows the greatest degeneracy?

What did not occur in the proterozoic eon a)the oxygen levels increase greatly in the atmosphere, b)the emergence of the eukarya , c)muti cella’s eukaryotic organisms began to diversify, d)anaerobic bacteria kept thriving with more oxygen

Does anyone know what a poms statement is for biology? i don't know what it is and i have an assignment on it tomorrow, will award the best answer a brainliest!

Why does miranda have that particular vision of dr hildesheim answer?