Setup

A, B, C, and D sit around a circular table, all facing the center.

Clues

1. A sits opposite C.
2. B sits immediately to the right of A.

Question

Who sits opposite B?

Answer

D sits opposite B.

Solution

1. Fix A at the top and place C opposite A.
2. Because all face the center, A's right is anticlockwise; place B there.
3. The remaining opposite seat belongs to D.