Spain felt that Portugal would dominate the world's trading routes and resources and it motivated them to compete with them and invest into their own campaigns, such as the one of Columbus.
Option A is the right answer.
Began around 10,000 B.C, the Neolithic revolution in the history of Human marks the transition from small nomadic bands of hunter-gatherer to larger agricultural settlement and early civilization. People in the Paleolithic age used Primitive stone tools, whereas tools in the Neolithic era were more sophisticated. People during this age invented new types of tools such as sickle blades and stone axes etc. People in the Paleolithic age lived in small groups of 20- 30 people in caves, or in cabins made of tree branches, while, the Neolithic people with the advent of agriculture and raising cattle moved to settle as the farmers and villagers.
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>
