Research about social media application

I want someone who can do research about the privacy of theses application.

1.      How do the following social networks deal with privacy in their terms of service? (for example, what type of information they collect, for what reason, and who can access these information from third parties )
a.      Facebook
b.      Twitter
c.      Instagram
d.      Snapchat
e.      LinkedIn
2.      Which social network between Facebook, Twitter, Instagram, Snapchat and LinkedIn provide the best privacy policies to its users?
3.      Why do most social network users not read the terms and conditions before joining these services?