Final answer:
Sharing user information with third-party advertisers is an inappropriate use of the collected information on the social media site.
Step-by-step explanation:
The inappropriate use of user information collected on a privately owned teenage sports club social media site would be b. Sharing user information with third-party advertisers. This would violate the user's privacy and potentially expose them to unwanted advertisements or spam. It is important for organizations to respect users' privacy and only use their information for purposes that are agreed upon in the terms of use and privacy policies.