Read the following passage and answer the questions by choosing the best answer among A, B, C or D.

Over the past 600 years, English has grown from a language of few speakers to become the dominant language of international communication. English as we know it today emerged around 1350, after having incorporated many elements of French that were introduced following the Norman invasion of 1066. Until the 1600s, English was, for the most part, spoken only in England and had not extended even as far as Wales, Scotland, or Ireland. However, during the course of the next two centuries, English began to spread around the globe as a result of exploration, trade (including slave trade), colonization, and missionary work. That small enslaves of English speakers became established and grew in various parts of the world. As these communities proliferated, English gradually became the primary language of international business, banking, and diplomacy.Currently, more than 80 percent of the information stored on computer systems worldwide is in English. Two thirds of the world’s science writing is in English, and English is the main language of technology, advertising, media, international airports, and air traffic controllers. Today there are 700 million English users in the world, and over half of these are nonnative speakers, constituting the largest number of nonnative users of any language in the world. 

What is the main topic of the passage?