#### Answer

The vertices which are adjacent to vertex D are vertex B, vertex C, and vertex E.

#### Work Step by Step

If there is at least one edge connecting two vertices in a graph, the vertices are adjacent to each other.
There is an edge connecting vertex B and vertex D, so vertex B is adjacent to vertex D.
There is an edge connecting vertex C and vertex D, so vertex C is adjacent to vertex D.
There is an edge connecting vertex E and vertex D, so vertex E is adjacent to vertex D.