Which is an example of a substitution mutation?
o cag - tta-cac mutates to cag - gac - tta - cac
cag - tta - cac mutates to cag - tta - cac-at
cat - ggc - tac mutates to cat - ggc - tag
cat - ggc - tac mutates to atg - gct - ac

CAT - GGC - TAC mutates to CAT - GGC - TAG is the right answer

Explanation:

because substitution mutation is the change in the single base which result in change in codon which encode different amino acid  and protein sequence changes.

for example in this

CAT - GGC - TAC  encodes HGY protein

now after change in single nucleotide from C to G

CAT - GGC - TAG which encodes HG stop codon

"a.) well–developed vascular system."