Verified answer

The sign convention is from the perspective of a working heat engine. So if you add heat to the system, it is positive. If you get work out of it, it is also positive. So the answer heat flow into the system is positive, and work is positive when it is done by the system. No. 3.

It depends completely on the conventions of books. there are differences. In most of the engineering books, the work done by the system is considered positive and that is because in engineering the aim is to get work from system, however in most of the physical texts, the work done by the system is considered negative because they just want to analyze the system. I think the flow of heat is considered positive when is from ambient to the system. so 1 and 3 are both applied.