1. Him
2. It
3. Us
4. Them
5. You
6. Her
Here is a picture of what I answered (I had this question on a test)
I'm not too sure about this. However, I would say that it is Ok to say attached is the assignment. It seems wrong, but to make it seem more natural, maybe try adding extra words like requested.
The answer is A. Think about what his interests are or ask others to input.
