A、Previous surveys. B、Experiments. C、Employees’ complaints. D、Researchers’ observations. A

A company mobile phone or laptop might seem like a benefit of the job but it could spell disaster for personal relationships, a new study has found. (19) Modern gadgets which allow workers to be perpetually on-call or able to check emails can put a huge strain on life outside of the office.
     (20) A British study, carried out by psychologists from the University of Surrey, analyzed 65 previous surveys involving 50,000 employees to determine the consequences of having constant access to work. They found that those who "switched on" long after the office was shut were more likely to have problems with their health and private lives. (21) The use of mobile phones and laptops increasinglyblurred the boundaries between work and home life, "causing work-family conflict," the authors concluded. The studies showed that although smartphones and tablets are often billed as helping to workers to be more flexible with their time, they actually caused employees to work longer hours. The researchers discovered that workers increasingly face a strong expectation to be available 24/7 and few feel able to switch off.
    Svenja Schlater who led the study said bosses needed to rethink whether it was sensible for employees to be in constant contact. " Staying ’ switched on’ might increase flexibility and efficiency at first glance, but in the long run, it can result in longer work hours and can be detrimental to wellbeing due to stress and work-life balance issues," she said. (22) "Researchers, employers and employees need to work jointly on how to make the use of technologies as beneficial as possible, reducing the negative effects. Otherwise, there is a danger of unintended knock-on effects.
19. What is the benefit of the company mobile phone or laptop?
20. Where does the data of the study carried out by the University of Surrey come from?
21. What is the conclusion of the study?
22. What suggestion does the leading psychologist Svenja Schlater put forward?