I use LibreOffice! Calc, Draw, and Writer are very user friendly once you get used to where the tools are. Impress is a pretty good replacement for Powerpoint: the stock graphics leave a lot to be desired--but that's a simple fix with a good stock image service. About the only thing LO doesn't do is notes, but I'd check out Xournal++ if you were looking for a way to replace OneNote. Plus, LibreOffice doesn't push OneDrive down your throat. It's been a win-win for me.
Another thing to consider if you really like typesetting is to learn LaTeX: it's a slightly steep learning curve(especially for advanced topics), but it'll do things that your typical WYSIWYG word-processing suite couldn't dream of doing. Plus there are a lot of templates available that you can adapt for your purposes.
Solving this problem is easy, if A or D were correct, P = 0.5, if C or B were correct P = 0.25, since A and D require P = 0.25, and since C and B require P = 0 or 0.5 respectively, there is no correct solution that can be given, therefore the solution is "Undefined".
Anyway, have a good troll!