The normal to the curve x = a(cos θ + θ sin θ), y = a(sin θ - θ cos θ) at any point θ is such that
(a) it is at a constant distance from the origin
(b) it passes through (a pi/2, - a)
(c) it makes angle pi/2 - θ with the X-axis
(d) it passes through the origin
