Decreasing total business logistics costs as a percentage of the U.S.GDP may be attributed to:

A) deregulation of the transportation sector.
B) an increase in global supply chains.
C) improved logistics technology systems and e-commerce.
D) deregulation of the transportation sector and an increase in global supply chains.
E) deregulation of the transportation sector,and improved logistics technology systems and e-commerce.

The decreasing total business logistics costs as a percentage of the U.S. GDP can be attributed to a combination of deregulation of the transportation sector and an increase in global supply chains, as well as improved logistics technology systems and e-commerce. Deregulation has led to increased competition and more efficient transportation options, while global supply chains have enabled businesses to access cheaper sources of inputs and reach new markets. Improved logistics technology systems and e-commerce have also helped to streamline operations and reduce costs.