The protostome developmental sequence arose just once in evolutionary history, resulting in two main subgroups—Lophotrochozoa and Ecdysozoa. What does this finding most likely suggest?

It is true that the protostome developmental sequence arose just once in evolutionary history.

Explanation:

During evolution the Bilateria had been into two major divisions. One was the protostomes and another was the deuterostomes. It is all categorized during the embryonic development.  

It is differentiated by the formation of anus and mouth. The protostomes include the annelids, molluscs and arthropods. Studies reveal that Protostomes are derived from their prebilaterian ancestors.

The protostome developmental sequence has been aroused only once during evolution which lead to the evolution of more than thousands of new species. They then were subdivided into two major group, namely Lophotrochozoa and Ecdysozoa.

regarding the law, the 15th amendment was specifically designed thinking in the rights of black free men.

even though ratified on february 3, 1870, the promise of the 15th amendment would not be fully applied for a long time.poll taxes and literacy tests would allow southern states disenfranchise african americans. only in 1965 the voting rights for african americans would be actually able to vote in the south.

in 1965, president johnson signed the voting rights act, which aimed to overcome legal barriers that prevented african americans from voting as it was guaranteed by the 15th amendment to the u.s. constitution.

the answers are a b and d