Read the following passage and mark the letter A, B, C, or D to indicate the answer to each of the question.

The world's population reached five billion on the day I was born. That was in Indonesia back in 1987, and my parents were amazed that there were so many people on the planet. However, since then the population has continued to increase.

The growth of our human population is extraordinary. For more than two million years, humans lived with no permanent home, finding plants to eat and hunting animals for meat. Then, just 10,000 years ago, we invented agriculture. At that time, there were only about five million humans, but this fgure quickly doubled. The population reached a billion in 1805, and since then it has multiplied seven times.

The human population has never been bigger, but in some ways the planet seems to be getting smaller. In the past, travellers from Europe to Indonesia spent months at sea. Now you just have to sit on a plane for a few hours. When you arrived in another country a hundred years ago, you saw unfamiliar styles of clothing and architecture and discovered a completely different culture. In many places today, clothing and new buildings are very similar, and people enjoy the same sports, music, films and TV shows. We also buy the same products from huge, global companies. In our different continents, we are starting to live the same lives. Even the languages that we use are becoming more global. There are around seven thousand languages in use today, but the number is decreasing fast.

The same thing is happening around the world. Experts think that the number of different languages will halve to just 3,500 by the end of this century. Where will it stop? Will there be a time in the future when Earth's billions all speak just one language, and there are no cultural differences to divide us? Perhaps the planet would be more peaceful if this happened, but I must admit that the idea is quite depressing. I prefer to think that, as our population grows, we can celebrate not the similarity but the fascinating diversity of the human race.

(Adapted from Insight by Roberts and Sayer)

The word “discovered” in paragraph 3 is closest in meaning to _______.