Which of the following statements is true about Facebook?

Alternative "d" is the correct answer. Alternative "a" is incorrect because Facebook is the social network with the most registered users. Alternative "b" is incorrect because in the past Facebook was a "closed system" and did not allow outside search engines such as Google or Bing to catalogue information about a brand or topic; later Facebook Pages, separate from private and personal profiles, were created as a method for brand managers to generate awareness for their product, service, or brand within Facebook. Facebook Page information is generally public and catalogued by search engines. Alternative "c" is incorrect because YouTube is the social network where users upload more videos to the website than any other social network.