Which of the following is not a reason why historians study societal change

option b, all states follow similar rules and legal process is the right answer.

the 14th amendment in the constitution of america was enacted in july 1868, which include the citizenship, due process, and the equal protection under the law. this amendment was a response to the issues related to former slaves following the american civil war.

the citizenship clause granted citizenship to all persons born or naturalized in the u.s,.   due process of clause asserted that states may not deny any person "life, liberty or property, without due process of law and the equal protection clause declared that a state may not deny to any person within its jurisdiction the equal protection of the laws. the above mentioned excerpt from the constitution of the united states, ensures the citizenship,due process, and equal protection under the law.