If a normal chord of $\mathrm{y}^{2}=4 \mathrm{x}$ subtends a right angle at the vertex, then the extremities of the chord are
(a) $(3, \pm 2 \sqrt{2}),(2, \pm 4 \sqrt{2})$
(b) $(2, \pm 2 \sqrt{2}),(8, \mp 4 \sqrt{2})$
(c) $(3,4 \sqrt{2}),(2, \sqrt{2})$
(d) $(3, \pm 2 \sqrt{2}),(8, \mp 4 \sqrt{2})$