China was one of the first civilizations in the world. This civilization, unlike the others, was actually very isolated from the rest of the ancient civilizations. The main reason for the isolation were the natural barriers. Between China and the other civilizations were standing the largest mountain range in the world, the Himalayas, and several large deserts. This discouraged people both from China and from the other civilizations from moving through this areas and see what's on the other side. This resulted in developing a very unique culture in China that was not influenced by any other culture. Also, this civilization was developing totally independently, and it actually managed to surpass the other civilizations in many aspects, while they were not even aware of its existence, or just knew that it existed but had no real idea about it. China only opened up properly to the world after it was invaded and ruled by the Mongols.
D, If you buy two new games, your opportunity cost is the time you could spend talking on the phone.
Explanation Opportunity cost is the value of the next best thing you give up whenever you make a decision. In this case the opportunity cost of buying the two games is the time you could be using the phone.
