Geometry

Question Analysis：
This question is about finding the additional information needed to prove using the ASA (Angle - Side - Angle) congruence postulate.
The key is to match the options with the requirements of the ASA postulate.

Key Concept Explanation：
The ASA postulate states that if two angles and the included side of one triangle are congruent to two angles and the included side of another triangle, then the two triangles are congruent.

Step - by - Step Solution：
We already know one side in each triangle is congruent (marked in the figure).
For ASA, we need angle - side - angle congruence.
Option D gives , which, together with the congruent side and another possible angle congruence, can meet the ASA criteria.

Option Analysis：
- A. : Just side - side equality, not relevant to ASA's angle - side - angle requirement, so it's incorrect.
- B.