Since it is so early in the year, it's doubtful that one "bad" SAC score will drastically remove your chances to get a 40+. Use the result as a wake-up call to inspire more study and to get better. Don't bog down in being disappointed in yourself or worry about the future, otherwise you're wasting time and will compromise your chances further. Focus on the present and use the past to push yourself forward, not to dwell on.
Look back on the SAC and what exactly made it substandard. What is the common theme between the things you got wrong? Is it the way you expressed your answer? Did you simply misunderstand the material? Did you not prepare enough beforehand?
If you still have the opportunity, have a meeting with your teacher about how to improve the answer and analyse how exactly you got something wrong. Then, write in some corrective colour (I use green) next to the answers you got wrong and annotate what would've helped. That way you not only consolidate what you did wrong, but also have a permanent record to check back on later if you'd like a refresher or reminder on how to solve a question.
Again, don't use a disappointing result as something to be put down by. Use it to your advantage and learn from the mistake by correcting yourself and using it as a wake-up call to keep persevering. Everybody will receive multiple failures and disappointments, even the top students, but they know how to be resilient and keep going faster and harder with their studies.