Under the conformal mapping $w = 1/z$, the circle $|z| = R$ in the $z$-plane maps to:
(A)
A circle of radius $1/R$ centered at origin in the $w$-plane
(B)
A straight line passing through the origin
(C)
An ellipse in the $w$-plane
(D)
A parabola in the $w$-plane