With respect to a variable point on the line x−y=2a, the chord of contact of the circle x²+y²=a² is drawn. If it passes through a fixed point F, then:
a) F lies on the line x−y=2a
b) F lies on the circle x²+y²=a²
c) F is the point of intersection of the line x−y=2a and the circle x²+y²=a²
d) F lies on the chord of contact