Answer:
Once again I'm here to prove the top one is correct.
Explanation:
Some 95% of frog species examined to-date, including Xenopus, the current model frog, possess homomorphic sex chromosomes 67, 68. Why and how sex chromosome homomorphism is maintained in so many species of this (often evolutionarily ancient) group is a mystery.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4091447/
