Here are the words that don't belong to each group:

1. **A. for** (doesn't fit with the conjunctions)
2. **A. bought** (doesn't fit with the conjunctions)
3. **A. club** (the other words are types of clubs)
4. **C. student** (the other words are various subjects)
5. **A. website** (the other words are types of discussions)
6. **B. forum** (this is a different type of interaction)
7. **B. teacher** (the other words refer to participation)
8. **C. participate in** (the other phrases imply taking part)
9. **C. uncle** (the other words are related to academic terms)
10. **D. social media** (the other words pertain to actions)

Let me know if you need further assistance!