Section B Directions: There are 2 passages in this section. Each passage is followed by some questions or unfinished statements. For each of them there are four choices marked A, B, C and D. You should decide on the best choice. There may have been few things that protesters, politicians and activists share, but during the G20 meeting, they were united by their use of Twitter. The micro-blogging service was heavily used by all those involved with the meeting, be they debating in the chamber, quizzing politicians after briefings, or protesting in the street. Social media was in use prior to the event too. The Metropolitan Police analyzed activity on websites such as Facebook, MySpace and many others to see how many were likely to join the call for protests at the G20. Plans for how many policemen and women should be put on the streets during the G20 were drawn up with regard to this analysis. But it was during the two-day event that social media, in particular Twitter, came in to their own. Thousands of messages marked with a G20 tag passed through Twitter and organizations such as Indymedia had their own tags 'that helped to examine information about what happened during the protests. For some campaigners, Twitter was-essential in giving the outside members a glimpse of what was happening inside the building of conference and it also let them know about the questions other campaigners were putting to politicians and their efforts to get their message across to the leaders of G20 nations. Many groups used Twitter as a way to reach out to supporters more quickly than they could with e-mail or text messages. Actually, with computer access literally thin on the ground, Twitter was the best option for reaching everyone. For instance, the Climate Change campaigners who set up the camp on Bishopsgate used Twitter to rally supports to carry supplies—namely baked potatoes and beans—to the site where they planned to set up tents. It was also used to send regular updates as the camp was being set up and to let people know how it was progressing. As a spokesman of this group said, Twitter had been invaluable in, helping smooth the organization. For many others, Twitter was a way to find out about and get to the independent media reports from people caught up in the protests. Using Twitter as an unofficial notice-board let those who had lost touch on the ground find out what had happened to friends and fellow protesters during and after the police clear-up. Friends concerned about what had happened to people they knew were reassured to see messages from them posted on Twitter reporting that they were fine. What does the author mean by saying 'they were united by their use of Twitter'(Line 2, Para. 1)?