Question

What is the simplest way to permanently get rid of an unwanted file?

Answer 1

Now, I suspect the answer is c. As this is how to "delete a file". For the same result, in windows, you can hold shift then press delete, and it will permanently delete it in the same way. 

However, when you a delete a file, the file is not physically removed from the disk until that files sector('s) (sectors are the smallest addressable unit of a hard drive) is overwritten (works a bit differently for ssd's).