Setup

D, E, F, and G sit in a row facing north.

Clues

1. D sits at the left end.
2. E sits at the right end.
3. F is not adjacent to D.

Question

Who sits next to D?

Answer

G sits next to D.

Solution

1. D is in position 1 and E is in position 4.
2. F cannot be in position 2 because it would be adjacent to D.
3. F takes position 3, leaving G in position 2 next to D.