Which criterion uses two angles and the included side?

• A. AAS
• B. SAS
• C. ASA
• D. SSS

Answer: (C)

The key idea is a triangle congruence rule that uses two angles with the side between them. If two angles of one triangle equal two angles of another triangle, and the side between those two angles is also equal, then the triangles are congruent. The two angles fix the third angle, and knowing the length of the side between the given angles locks in the size as well, leaving no freedom for a different shape. That combination—two angles plus the included side—is exactly what guarantees congruence.

So the criterion described is the Angle-Side-Angle rule: two angles and the included side determine a congruent triangle. Other options mix different pieces (two angles with a non-included side, two sides with an included angle, or all three sides), which is not the same combination.