Through what means of transportation do scientists believe most human ancestors used to migrate from africa to other regions?

a. walking over land bridges

b. boating across the atlantic ocean

c. traveling by horse-and-buggy

d. sledding with animal hides

The correct answer is Walking over land bridges, i took the test.

it provided for selection of government employees through competitive examinations. it also made it unlawful to fire or demote covered employees for political reasons or to require them to give political service or payment, and it set up a civil service commission to enforce the law.

explanation:

the doctrine of nullification recommended that states living inside the union have the one-sided, inalienable ideal to void any law made by the national government that could be esteemed illegal.

the united states was shaped based on a general agreement among its individual states. hence, it is inferred that under the hypothesis of invalidation, since the states are the establishment of the union, they have the ability to referee and disprove unlawful laws.