The 1874 Samuel Lockett geological survey identified Louisiana’s 5 major natural regions: Mississippi Floodplain, , Terraces, Marshes, and Hills.

b. marked the most important change in the U.S. Constitution since the Bill of Rights.        

Explanation:

           The Constitution of the United States is the written legal document of the United States federal government according to which the function and the structures of the U.S. government works. It also provides the basic rights to the citizens of United States.

          The Bill of Rights of the U.S. Constitution is the first ten amendments that guaranteed certain fundamental rights to the U.S. citizens such as freedom of speech, worship and assembly, etc.

           The fourteen amendment to the United States' Constitution was ratified in the year 1868. It provided citizenship to the people through naturalization or by birth in United States to all including the former slaves and granted equal protection to all the citizens of the laws.

Hence the correct option is (b).