Answer:
D Taming animals for human use. Hope I helped :)
The United States wanted to build the Panama Canal in order to save time and money on trading. Before the Panama Canal, people had to sail all the way around Africa in order to get to the other side of the world, which costed much more money and took a lot longer. The US owns the canal because of the Hay-Bunau-Varilla treaty, which gave the rights to the USA to build and manage it.
The U.S. reluctance to send Americans to fight in foreign countries for fear of getting the U.S. involved in another Vietnam is called "D<span>. the Vietnam syndrome," since the Vietnam War was viewed by many as being a foreign policy disaster. </span>
