All of the above (correct me if I’m wrong) :)
(C) Problem Solving skills (D) Math skills and (B) research skills
The internet affects collective behaviour, because it spreads ideas and opinions rapidly, and can be viewed by many people. The internet is a strong tool that can be used to change people's perspectives and can make people do what they previously would not think of doing (for example; trends).
What answers are you looking for exactly?