Geometry

Question Analysis：
This question checks your ability to identify shared parts between two triangles.
The main focus is on common sides.

Key Concept Explanation：
△ABC and △DBC both touch points B and C
So, the only shared segment is BC
Point A and segment AB are only in △ABC
Angle D belongs only to △DBC

Step-by-Step Solution：
Look for overlap between △ABC and △DBC
Both share base BC
Other parts (like point A or line AB) appear in only one triangle

Option Analysis：
A. Point A ❌ — Only in △ABC
B. Line segment BC ✅ — Shared side
C. Angle D ❌ — Only in △DBC<...