I’m assuming since you can take Ritual Magic in the second semester that you didn’t take it in the first.
If you took Potions, then you might have a chance of surviving Ritual Magic. Since the two stats are tied together, you might have done enough in that subject to have a (at the very least) mediocre start in Ritual Magic.
If you took Combat, however, then avoid Ritual Magic at all costs and go with World Studies. Your Ritual Magic/Potions stat will be extremely low if you don’t take any of those two subjects, and trying to focus on a low stat halfway through the game is more than likely going to result in failure. Besides, World Studies relies on Intelligence, a stat which you had plenty of opportunities to raise, regardless of your classes.
If you have low numbers in both Ritual Magic/Potions and Intelligence, well…I’ve got nothing for you.