Why does Facebook motivate the productivity of employees?

Câu hỏi: Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions.
Facebook users spend an average of more than 15 hours a month on the social networking site. While there are plenty who caution against such intensive use — and there are a number of studies detailing the harm Facebook could potentially cause — there also are lots of reports extolling the site's virtues. As the social media giant prepares for its upcoming initial public offering, here are some ways Facebook just might be good for you.
Spending time on Facebook can help people relax, slow down their heart rate and decrease stress levels, according to researchers from the Massachusetts Institute of Technology and the University of Milan. In a study published earlier this year, researchers studied 30 students and found that a natural high was sparked when they were on the social media network that led to the relaxed heart rates and lower levels of stress and tension. In the study, the students were monitored in three situations: looking at panoramic landscapes, performing complicated mathematical equations and using Facebook. While the first situation was the most relaxing to students and the math problems were the most stressful, the time on Facebook uncovered high levels of attractiveness and arousal. The findings support the researchers' hypothesis that Facebook's success, as well as that of other social media networks, correlates to the specific positive mental and physical state users experience.
While many may argue that social media networks only distract employees, research shows the opposite may be true. Research from Keas.com found that a 10-minute Facebook break makes employees happier, healthier and more productive. The study examined workers in three groups: one that was allowed no breaks, one that was allowed to do anything but use the Internet and one that was allowed 10 minutes to use the Internet and Facebook. The Facebook group was found to be 16 percent more productive than the group that was not allowed to use the Internet and nearly 40 percent more productive than the group that was allowed no breaks. "Short and unobtrusive breaks, such as a quick surf on the Internet, enables the mind to rest itself, leading to a higher net total concentration for a day's work, and as a result, increased productivity," said Brent Coker of the department of management and marketing at the University of Melbourne in Australia.
Facebook is also in the business of matchmaking. Research shows that nearly 60 percent of singles will friend someone new on Facebook after meeting them in person. If they like what they see, 25 percent are likely to contact their new love interest via Facebook. Once the courting is over, nearly 40 percent of those social networking adults will update their relationship status on Facebook, with just 24 percent telling their friends first. Facebook use between couples will continue through the dating process, the research shows. Throughout the day, 79 percent of couples said they send partners Facebook messages or chat on the social network. In addition, more than 60 percent would post romantic messages on their significant other's Facebook wall. When the relationship ends, more than half of those surveyed immediately update their status to single, which automatically sends out a notification to their friend list to start the dating cycle over again.
(Source: https://www.businessnewsdaily.com/)
Why does Facebook motivate the productivity of employees?
A. Because the Internet distracts users to take breaks out of work.
B. Because it helps people refresh their mind and then enhance the concentration on work.
C. Because employees are happy with what they read on the Facebook.
D. Because they are allowed to relax after a hard work.