An Operating System is a set of programs that coordinates all activities. All activities among software and hardware.
Software, unless you planned on permanently downloading the Music Album or Song to your computer's Hard Drive. i.e, you would use whatever Music or Media player you have installed on your computer, and that simply counts as Software.
hope this helps.
I personally would use Word because it has the potential to create the cover letter and attach a resume along with it.
Excel is more for tables and creating an organized way to see your recordings.
PowerPoint is known for presentations mainly.
Twitter is a type of social media platform that is useful in communication.
Probably the minimum number in the given set so 5.