45.Which of the following is the best title for the passage？
(A)Survey Findings of Social Media Use in the U.S.
(B)The Uses of Facebook and YouTube Are on the Rise
(C)The Differences between Facebook and YouTube Users
(D)The Untold Story of Social Media in the U.S.

*emerging 新興的

*narrative
故事；敘述
a story or a description of a series of events
It's a moving narrative of wartime adventure.
（對事件的特定的）陳述
a particular way of explaining or understanding events
There was pressure on academics to construct narratives of the period that were positive.
Both sides in the conflict have a narrative of victimhood.

*sizeable相當大的(數量)

*demographic
人口的；人口統計的；人口學的
relating to demography (= the study of populations and the different groups that make them up)
There have been monumental social and demographic changes in the country.
（顧客）族群
a group of people, for example customers, who are similar in age, social class, etc.
This demographic (young teenagers) is the fastest-growing age group using the site.

資料來源：劍橋辭典