Final answer:
Two sets of congruent angles are required to prove that two triangles are similar, as per the Angle-Angle (AA) similarity postulate.
Step-by-step explanation:
To determine if two triangles are similar, we need to compare their corresponding angles.
According to the Angle-Angle (AA) similarity postulate, if two angles of one triangle are congruent to two angles of another triangle, then the triangles are similar.
Therefore, the answer to the question, "How many sets of congruent angles are needed to prove that 2 triangles are similar?" is B. 2.