Question

which discovery provides the most evidence to support the idea that two species may have had a common ancestor?
they possess four limbs which they use for movement.
they reproduce sexually.
they have a high percentage of similar genes.
they live in the same habitat.

Explanation:

Genetic similarity (high percentage of similar genes) is a strong indicator of a common ancestor. Habitat (where they live) can be similar due to convergent evolution (not common ancestry). Reproducing sexually is a common trait among many unrelated species. Having four - limbed movement (if due to convergent evolution, not a sign of common ancestry). But similar genes directly point to a shared genetic heritage from a common ancestor.

Answer:

They have a high percentage of similar genes.