The fourth alternative is correct (D).
English is the most popular language in the world. In addition to English speaking countries such as the United States and England, English is also universally used in business and is the main language of international organizations such as the UN and the IMF.
Even in developing countries, people seek to learn to speak English in order to differentiate themselves in the labor market. In the case of immigrants, learning English is especially important, since they are in a country with an English language, so that speaking English facilitates the communication of these people with the rest of the community.