These paragraphs explain why we can see colors other than green, red, and blue―even though the cones in our eyes are sensitive to just those three colors. Since you have just three types of color detectors in your eyes, it would make sense that the only colors you see would be red, green, and blue. But suppose you're looking at a yellow object. How would your eyes detect a color that isn't an exact match to one of the cones? In this case, the different wavelengths of light for both red and green are reflected into your eyes. The red and green cones send signals of varying strengths to your brain, depending on how excited they are by the different wavelengths. For example, the red cones would be very triggered because more red light is reflected from a yellow object. The green cones would also be triggered, but not as much as the red cones. This triggering of the three different cones to varying degrees is how you see all the different colors. How does this passage of text help readers understand its central idea? A: It defines key terms.
B: It tells a story.
C: It provides an example.
D: It describes a series of steps.

C: it provides an example, because it explains what is happening to trigger it.

English is the most commonly spoken language in the world. One out of five people can speak or at least understand English! English is the language of science, aviation, computers, diplomacy, and tourism. Knowing English increases your chances of getting a good job in a multinational company within your home country or of finding work abroad. English is the official language of 53 countries and is used as a lingua franca (a mutually known language) by people from all around the world. This means that whether you’re working in Beijing, or travelling in Brazil, studying English can help you have a conversation with people from all over the world. In the last century, the number of scientific papers written in English has started to outweigh the number of papers written in the native language of the researcher. In the Netherlands, for example, the ratio is a surprising 40 to 1. For this reason, having a knowledge of English is incredibly important to those working in the scientific field. Because of the prominence of Hollywood in global media, an enormous amount of films, TV shows and popular songs are written in English. If you speak English, you won't need to rely on translations and subtitles anymore to enjoy your favourite books, songs, films and TV shows. English is a particularly important language online with more than half the content on the internet written in English. As well as this, some of the world’s largest tech companies are based in English speaking countries.