The languages of ancient Egypt, Babylon, and ancient Maya, which were once prevalent in history, have become a historical dust, and more than 6,000 existing languages in the world will disappear on average every two weeks. From this calculation, by 2050, the world 90% of the languages will be extinct. Which of the following, if true, would best refute the above point? ['Many linguists are studying these languages.', 'Ancient languages are often extinct as civilization is conquered.', 'Many endangered languages have been valued and effectively protected.', 'The proportion of non-illiterate people in modern times is significantly lower than in ancient times.']