Which experimental approach would be the most effective and easiest to clearly determine the evolutionary relationship between these two organisms?

An image of an orange sea star is shown. A photo shows a bright green snake wrapped around a branch.
A. Sequence the same gene in both species to compare their similarity.
B. Dissect specimens of both species to look for homologous structures.
C. Search fossil databases to locate a common ancestor.
D. Evaluate cells from both species to determine whether they contain enzymes.