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.

the underground railroad (apocope of the metropolitan railroad) is a system of urban trains located within a city and its metropolitan area. it is characterized for being a massive transport of passengers in the big cities, uniting diverse zones and their environs, with high capacity and frequency and in segregated form to other systems of transport. metropolitan railroads are built underground or on the surface, although most systems use mixed models where sections are combined in both modalities.

1 - as a result, the metro tends to reduce car travel for two reasons: first, due to the greater transfer of users from the car and, second, due to the reduction in the acquisition of cars in homes located in sectors near the stations of the metro.

2 -the metro allows to contribute effectively to the achievement of all the objectives of an urban development policy: it improves the efficiency of the city's economy by reducing travel costs and also generates a higher level of activities in the city center, taking advantage of of the agglomeration economies.

3 -it is a clean means of transport, since it uses renewable energy (usually electricity), taking care of the environment and avoiding excessive pollution.

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