Which of the following is a software application program?

In my opinion would also qualify in most cases. I consider utility software like CCleaner, Antivirus software, and other system clean-up products, applications. I think the author of the question is trying to distinguish between utility software that does work on the system and software geared to "real world" tasks like browsing the web or creating documents.

PeNgUiNz RuLe has an even wider definition than I do, but I see some merit in what he is saying. OS's are applications that allow you to manage files and work with other applications. Theoretically, compiler could be a standalone application. You could open it and feed it a text file with code and it could kick out an executable file. More often than not these days compilers are parts of bigger applications called IDEs (Integrated Development Environments). A good example of this in Windows is Microsoft Visual Studio Express. You can write code in it and then use the compiler to create an executable file.