Concept:Points equidistant from two fixed points lie on the perpendicular bisector of the segment joining them.Solution:Amadu is always the same distance from P and Q, so AP=AQ.The locus of points satisfying AP=AQ is the line that meets PQ at its midpoint and is perpendicular to PQ.Therefore, the correct description is the perpendicular bisector of line PQ.Answer:Option D (Perpendicular bisector of line PQ)