2002 Chevy Malibu - General questions

Can anybody tell me how many O2 sensors a 2002 Chevy Malibu has and where they are located? I have an idea and think I see them, but I don't want to make a mistake. And looking under my car I see two compartments that look like I would have two Cat converters. Is that correct or is it just one Cat?

one cat, there are tow 02s, one pre cat and one post cat

one cat, there are tow 02s, one pre cat and one post cat