Geometry

Question Analysis:
This question tests knowledge of valid triangle congruence postulates and whether SSA is a valid condition.

Key Concept Explanation:
SSS (Side-Side-Side): Valid. If all three sides are equal, the triangles must be congruent.
SAS (Side-Angle-Side): Valid. If two sides and their included angle are equal, the triangles are congruent.
SSA (Side-Side-Angle): Not always valid (ambiguous case).
ASA (Angle-Side-Angle): Valid. If two angles and their included side are equal, the triangles are congruent.
AAS (Angle-Angle-Side): Valid. If two angles and a non-included side are equal, the triangles are congruent.

Step-by-Step Solution:
SSS (A) is valid since three equal sides ensure congruence.
SAS (B) is valid since two sides and the included angle uniquely determine a triangle.
SSA (C) is not valid because it can lead to two different triangles.
ASA (D) is valid since two angles and their included side ensure congruence.
AAS (E) is valid since two angles and a non-inc...