The locus of the foot of the perpendicular from the origin to chords of the circle x²+y²−4x−6y−3=0 which substend a right angle at the origin, is
A. 2(x²+y²)−4x−6y−3=0
B. x²+y²−4x−6y−3=0
C. 2(x²+y²)+4x+6y−3=0
D. 2(x²+y²)+4x+6y+3=0