Answer
The figure shows amino acid difference in hemoglobin as it shows relationships among organisms. The snake should have more amino acid differences from humans than the bird but less than the frog, which would place it on the tree between those two.
Work Step by Step
Amino acid differences usually accumulate over time after two organisms have diverged from one another, and the number of differences increases the longer ago the divergence occurred. Snakes emerged before the birds/last surviving descendants of the dinosaurs but after the amphibians/frogs. Thus, snakes should have more amino acid differences than the bird but less than the frog. This would place the snake between the bird and the frog on the tree.
