Answer:
B. by chatting with friends
C. by downloading violent or sexual content
Explanation: The immoderate use of internet can decrease Ryan's concentration for studying and lead him to explore deeper into the internet world. By having access to almost everything online, he can delve into online sexual content and develop interest in it. Since the content varies, it is most likely for Ryan to get attracted to violent content. Also, as a teenager, instead of using internet to gather information for a lecture or a test, he can quickly lose interest by being online with his friends constantly. Therefore, it is very important for parents to have some kind of control of the teenager's online surfing since it can deeply affect his concentration, mental health and view of sexual intercourse.