A particle is placed on the parabola y \equal{} x^2 \minus{} x \minus{} 6 at a point P whose y-coordinate is 6. It is allowed to roll along the parabola until it reaches the nearest point Q whose y-coordinate is \minus{}6. The horizontal distance traveled by the particle (the numerical value of the difference in the x-coordinates of P and Q) is:
<spanclass=′latex−bold′>(A)</span>5<spanclass=′latex−bold′>(B)</span>4<spanclass=′latex−bold′>(C)</span>3<spanclass=′latex−bold′>(D)</span>2<spanclass=′latex−bold′>(E)</span>1