Question

scientists compile many pieces of evidence to infer evolutionary relationships. here is one such piece of evidence.
the gene fgfr encodes a cell membrane protein, fibroblast growth factor receptor, that is involved in cell growth and division, wound healing, and the development of embryos. this table shows the number of nucleotides in the fgfr gene that are identical between three different animals: tunicates (a type of nonvertebrate chordate), hydras (a type of cnidarian), and ribbed newts (a type of salamander).
which claim is best supported by this evidence?
of the three species, tunicates and ribbed newts are most closely related.
of the three species, hydras and tunicates are most closely related.
of the three species, ribbed newts and hydras are most closely related.

Explanation:

In evolutionary biology, the more identical nucleotides (or genetic similarities) two species share in a particular gene (like FGFR here), the more closely related they are. Comparing the values: 250 (ribbed newts - hydras), 200 (hydras - tunicates), 443 (tunicates - ribbed newts). The highest number (443) is between tunicates and ribbed newts.

Answer:

Of the three species, tunicates and ribbed newts are most closely related.