Explain one bad grade

I’m applying to top 10 colleges and most of my grades, extracurriculars etc are pretty solid. I do have one C+ in a AP Calc AB class in 9th grade. The class was hard and I missed a test for a very important national level competition. I was not allowed to retake the test. Should I add this information in the additional information section? Would that create a full picture for the admissions officer or does it not matter?

Here is the advice that I would give a student:

If that’s your explanation, then no, you absolutely not talk about it.

Your best course is to have received A’s in your later STEM courses.

But since you’re either a parent posing as the student, or you’re a student sharing your parent’s account, I’ll also have to close the thread since neither is allowed

Deleted – thread is being closed.