Why did NASA send New Horizons spacecraft to Pluto?

In this section, you will hear five short news items. After each item, which will be read only once, there will be a twenty-second pause. During the pause, read the question and four choices marked A, B, C and D, and decide which is the best answer. Then mark the corresponding letter on the answer sheet with a single line through the centre.
16. NASA’s New Horizons spacecraft has made the first visit to Pluto, speeding past 14 km per second. Earlier, the space agency released the most detailed picture yet as it hurtled towards the dwarf planet on Tuesday. The probe was sent to grab more pictures and other science data on the planet, as it passed 12, 500 km from the surface.
17. The Swiss city of the Geneva is planning activities to regain the title of "Peace Capital of the World". Geneva is home to the United Nations European headquarters. Many peace negotiations have taken place in the city. The United States and Soviet Union met there to talk about controlling nuclear weapons. Other talks included ways to end wars in Afghanistan and Lebanon. Talks to end those wars took place in Geneva throughout the 1990s. They were led by the United Nations.
18. The American dictionary Merriam—Webstar’s 2015 Word of the Year is not even a word. It is a three-letter suffix—-ism. -ism is a noun suffix. Merriam-Webster, com defines it as the act, practice, or process of doing something. Major -ism words in 2015 centered on politics, beliefs and discrimination. Merriam-Webster chose its Word of the Year based on how many people look up each word in its online dictionary. It found that seven of the highest-ranking words this years ended in -ism.
19. Most recently, representatives from nearly 200 nations gathered in Paris to fight climate change. Almost every country agreed to limit the rise in global temperatures. They agreed that the world should not get any warmer than 2 degrees Celsius above what it was in the mid-1700s. This will require nations to reduce their greenhouse gases, like carbon dioxide. Those gases are released from the burning of fossil fuels, like oil and gasoline, and they are blamed for raising the temperature of the planet.
20. The British government reports that the country’s richest people are increasing their wealth three times as fast as the poorest. The report is adding to worries about inequality in Britain. The Office of National Statistics says the wealth of the richest 10 percent of British households increased by 21 percent between 2012 and 2014. It says much of the increase came from a rise in private retirement payments, called pensions. The wealth of the lowest half of all households increased by just seven percent during the same time.