I asked my teacher. He said C was wrong but he seemed confused when explaining. So why A is wrong? There is no "spend oneself time"? Save yourself time = Save your time ?
No, you can't "spend yourselt time." You can, however, "save yourself time," (or you can save someone else time). Or you can just save time. If you say "save yourself time" you are emphasizing that you are the one who will benefit from the time savings.