the y-intercept of a parabola is the y coordinate of the point where does the graph intersect the y-axis.
so from the figure, we can see that the parabola is intersecting the y-axis at (0, -6)
and it is intersecting the x-axis at (3,0)
thus. y-intercept is (0, -6) and x-intercept is (3,0)
that is option D