$GUU$ codes for

Out of $64$ codons,$61$ codons code for $20$ types of amino acids. This phenomenon is called:

Assertion : $UAA, UAG$ and $UGA$ terminate protein synthesis.
Reason : They are not recognised by $tRNA$.

Suppose evolution on Earth occurred in such a way that instead of $20$ amino acids,there were $96$ amino acids. If $DNA$ consisted of $12$ different types of bases and $DNA$ synthesis occurred in the same manner,what would be the minimum number of bases required for each $DNA$ codon?

The first codon discovered by $Nirenberg$ and $Matthaei$ was:

$A$: Polypeptide sequences are dictated by $DNA$ and represented by $mRNA$.
$R$: Sequence of amino acids in a polypeptide can be predicted by the exact sequence of nucleotides on the $mRNA$ and template $DNA$.