Suppose Three Sibling Species of Frogs Have the Following DNA

Suppose three sibling species of frogs have the following DNA sequences at a portion of a gene:
Species 1: AGTCTAGATCGCGGTCG
Species 2: AGTCGATCGCGGACG
Species 3: TGTCTAGATCACGGTCG

Recall that the observed number of mutations can differ from the total number of actual substitutions that occurred in pairwise sequence comparisons.If we assume that a gap of any length is equivalent to three nucleotide substitutions, how many substitutions have occurred between species 1 and species 3?

A) 1
B) 2
C) 3
D) 4
E) 5