Answer: 4 codon
Step-by-step explanation:
We have two important data, that a molecule brought from Mars uses only three bases (A, C and T) and that it has 30 amino acids
Knowing that to encode 30 amino acids with 3 bases, you need to have 4 bases in your codon.
We have the possibility that having 4 bases can be encoded enough like this:
3 ^ 4 = 81.
however if we do the same procedure with 3 basic codons we will get an insufficient result
3 ^ 3 = 27
so the most likely codon number is 4