Câu hỏi:

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct answer to each of the questions from 19 to 26. 

LIFE IN THE FUTURE

     By the end of the third millennium, people will have access to basic utilities like electricity and the internet. As a type of civilization, the overall energy consumption of everyone in the 30th century will be at a level of around 4x10²⁶ watts. In other words, the energy utilization in a world full of working class consumers will be comparable to the luminosity of our parent star. So, the people of the future will inevitably need to fully harness the output of the Sun through the use of a vast array of satellite mega - structures that encircle the celestial body and capture the radiation it emits. 

     In requiring everyone to work together, the inclusive attitude of the future will cause everyone to grow much closer to one another, improving interpersonal relationships in neighborhoods the world over. By the year 3000, the whole of humanity will become a sort of poly-amorous society of mono-ethnic global citizens, living in a complex egalitarian intercontinental cooperative. Everyone will be part of multicultural communities within communities. Companies and credit unions will even be owned by their employees.  People will be very conscientious. Everyone will support the global economy, as well as ecology, of the world. 

     Humans will inhabit artificial urban jungles filled with buildings and sidewalks, while the other animals will inhabit natural rural jungles filled with wilderness and trails, Friends will walk through the crowded streets of the mega-cities of the future holding hands with one another. Public displays of affection will be customary among everyone. Casual bisexual encounters will be the norm. Everyone will care about everyone else. People will all accept each other, and help each other out, more and more as time goes on. 

     The point is that eventually, everyone will finally get along. Humanity will progress to a point of collective compatibility as everyone sufficiently integrates and assimilates. From now until the year 3000, the several thousand languages currently spoken will reduce down to only about a hundred. More importantly, the nation state members of the UN will all use the same form of electronic currency. As the countries of the world unify more and more, the metric system will become the universal standard of measurement. Things will become increasingly more common among everyone. This will bring everyone closer and closer together, each step of the way. In the end, cultural memes will all eventually just blend together in the great melting pot that is the world.

     People will also change physically, along with mentally, too though. For instance, there will be an increase in both height and longevity, among people in general. In the year 3000, people will be about six feet tall, and live to be 120 years old, on average. They will experience a slight reduction in the size of their mouths, too. Improvements in nutritional science will revolutionize the world of medicine and alter the course of human evolution. Everyone will be genetically screened as an embryo to weed out defects and correct mistakes in their personal genome. 8^th scale transhuman cyborgs will even go so far as to have 7th scale robotic integrations, with microscopic machines making them better. This will be terribly important because there will be very little diversity in the gene pool of the superhumans of the future, who are all bred to be what is considered ideal. 

The word "that" in paragraph 4 refers to _______.