<span>The answer is D. Interstate Highway System. The United States envisioned a highway system that would allow for controlled access to the road with no stop lights and a higher speed limit. This would allow for a faster means of transportation for goods and people throughout the country. In modeling this highway system, the United States looked to the autobahn in Germany after seeing how successful it was.</span>
I know this isn't answering your question but i think you will find it useful to visit the link pasted below. i just visited it and it explains pretty much everything about this.
gas exchange occurs in the human lungs.
