4.0s are excellent ones

GPAS

Think of the two-letter abbreviation for the scale that measures academic success, where this answer represents the highest possible scores.

This clue plays on the idea of "4.0" as a perfect grade point average (GPA) in many grading systems. The word "excellent" hints that we're looking for a term related to high academic performance, and "ones" suggests the plural form of something measured numerically. Putting it together, "GPAs" fits because a 4.0 is the top score, making those GPAs the "excellent ones."