Which of the following is an assumption on which the argument depends? A. In general, the reason that the people in the studies had doubled their Internet use was not that they had earlier experienced a significant decrease in opportunities for face-to-face social contact. B. A sharp decrease in face-to-face social contact is the only change in daily activity that can lead to an increased incidence of depression. C. Using the Internet presents no opportunities for people to increase the amount of face-to-face social contact they experienced in their daily lives. D. Regular Internet users who are depressed will experience an immediate improvement in mood if they sharply decrease the amount of time they spend on the Internet. E. Before they doubled the time they spent on the Internet, the people who did so were already more prone to depression than are regular Internet users in general.