A, B and C; first, second and third
Used for three-grade classification, often in formal or grading contexts. The three characters represent the first three of the ten Heavenly Stems, used here as ordinal markers.
The results were graded as A, B, and C.
These documents are classified into three types: A, B, and C.
From the first three of the ten Heavenly Stems (甲, 乙, 丙), traditionally used for ordering and grading.