Here are the correct forms for each sentence:

1. What he detests to do is going to work at **the weekends**.
- **D: the**

2. All the girls in my class are a big fan of SNSD **girl bands**.
- **D: girl bands**

3. Going fishing alone is one of my Dad's favorite **leisure activities**.
- **D: leisure activities**

4. She sings that song **better** than I do.
- **B: better**

5. I think that she wouldn’t mind to go to the night party with you, **surely**.
- **C: surely**

If you need further assistance or clarification on any of these, feel free to ask!