Geometry

Question Analysis:
This question tests the ability to identify corresponding sides in congruent triangles based on naming order.

Key Concept Explanation:
In congruent triangles, the order of vertices determines side correspondence:
First vertex ↔ First vertex
Second vertex ↔ Second vertex
Third vertex ↔ Third vertex

Step-by-Step Solution:
Given ⊿ABC ≅ ⊿DEF, the correspondence is:
A ↔ D
B ↔ E
C ↔ F
Therefore:
AB ↔ DE
BC ↔ EF
AC ↔ DF

Option Analysis:
A: Incorrect (AB ↔ DE, not BC).
B: Correct (BC ↔ EF).
C: Incorrect (AC ↔ DF)...