An argument is sound if it is truthful and if it's valid. If all parts of it are valid and truthful, then the conclusion is also valid and truthful and therefore solid. That's why you should ask whether it is valid and true.
The rules you implied were not enforceable.
Hope that helps! :)
Answer:
the answer to this question is a
The second option. If you must bring a folder, at least bring the smaller one.