Given points A(x1, y1) and B(x2, y2), find the locus of point P such that angle APB is 90 degrees.

A) (x−x1)(x−x2)+(y−y1)(y−y2)=0
B) (x−x1)(x−x2)−(y−y1)(y−y2)=0
C) (x−x1)(y−y1)+(x−x2)(y−y2)=0
D) (x−x1)(y−y1)−(x−x2)(y−y2)=0