Adam smith’s explanations of national economic living standards became known as the theory..

Classical theory  

Explanation:

The classical theory is one of the type of traditional method that explain about the national economy standard in an organization for building an accounting model by using various types o business strategies.

According to the question, the Adam smith's explaining about the national economical living standards.

The main benefits of the classical theory is that it helps in providing the high quality, efficiency, management and cost reduction in the specific organization system.

 Therefore, Classical theory is the correct answer.  

it id the first and last option