<p>Leave it out. The “additional comments” section is for situations where you received an unusually low grade due to outside circumstances such as family problems, health issues, etc. – not because you were right on the borderline and your teacher didn’t round up. The difference between one C+ and one B- in your cumulative GPA isn’t very significant anyway.</p>
<p>If they’re actually interested in looking at each individual grade on your transcript, they’ll be able to see that you improved your US History grade to a B+ spring semester, which is an upward trajectory that works in your favor.</p>